28th Congress of SCTM

23 Sept 2026, 16:00 → 26 Sept 2026, 12:00 Europe/Zurich

Metropol Lake Resort

Marina Stefova (Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University in Skopje), Jasmina Petreska Stanoeva (Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University in Skopje)

Dear Colleagues,

On behalf of the Organizing and Scientific Committee of the 28^th Congress of the Society of Chemists and Technologists of Macedonia (SCTM), it is our great pleasure to invite you to participate and contribute to this event. The 28^th Congress of SCTM will be held in Metropol Lake Resort in Ohrid, N. Macedonia from 23^th to 26^th of September 2026.

Conferences are opportunities for exchange of ideas, scientific development of young scientists, establishing new collaborations and partnerships, visiting nice places and making new friends. Contributions from all areas of chemistry, chemical engineering and related topics are welcomed.

The registration and abstract submission deadline is August 20, 2026. 

  We invite authors to submit their contributions as oral (10 min + 5 min) or e-poster presentations (using the provided Template and following the Guidelines). The 28^th Congress of SCTM will award the best three poster presentations. 

The scientific disciplines that will be covered at this congress are given in the Scientific Sections. The template for the abstract can be found at the bottom of this page in the attachment section.

We kindly ask you to create an Indico profile (no payment is necessary for this) and send your abstracts at your earliest convenience once the submissions are available. The abstract's template can be found at the bottom of this page, in the attachment section.

Official e-mail address of the Congress: sctmacedonia@gmail.com

Yours sincerely,

Prof. Dr. Marina Stefova Scientific Committee, president Institute of Chemistry, Skopje, N. Macedonia

Prof. Dr. Jasmina Petreska Stanoeva Organizing Committee, president Institute of Chemistry, Skopje, N. Macedonia

The 28^th Congress of SCTM is a    recognized event. 

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Photo: Panoramic view of the church of Saint John at Kaneo, Ohrid. It was built before 1447 and has a cruciform architectural plan built into the shape of a cross, with a rectangular base. By Jakupica.

28-SCTM-e-poster template.pptx

28-SCTM-E-Poster-guidelines.pdf

28Congress-book-of-abstracts-template.docx

E-poster-online-submission-instructions.pdf

Thursday 24 September

09:30 → 10:15 Chemistry Matters: From a Putative Peptide to Effective Medicines for Diabetes and Obesity

In the 1960s and 1970s, considerable interest was directed toward understanding the role of peptides in glucose metabolism. Particular attention was given to incretins, intestinally secreted peptides that stimulate insulin release from pancreatic β-cells following food intake, thereby regulating glucose homeostasis. In parallel, research efforts focused on glucagon, a peptide secreted by pancreatic α-cells that increases blood glucose levels.
The presentation describes the research leading to the discovery of the biologically active sequence of glucagon-like peptide-1 (GLP-1), identified as the 31-amino-acid peptide GLP-1(7–37), and demonstrates that this peptide functions as an incretin with therapeutic potential for the treatment of type 2 diabetes. These findings are considered in the context of the broader body of work by other investigators that contributed to the understanding of GLP-1 biology.

Speaker: Dr Svetlana Mojsov (Rockefeller University, New York, USA)

11:00 → 11:30 Decoding Complex Mixtures: How LC-HRMS is Transforming the Detection of Emerging Contaminants

The increasing complexity of environmental contamination, characterized by mixtures of hundreds to thousands of known and unknown compounds, poses significant challenges for effective monitoring and risk assessment. In this context, advances in liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) have transformed the field of environmental analysis by enabling comprehensive and highly sensitive detection of a wide range of contaminants and molecular signatures in complex environmental matrices.

This talk will highlight the opportunities offered by HRMS for the identification of emerging contaminants, with a particular focus on suspect screening approaches. These strategies enable the systematic investigation of large numbers of compounds beyond conventional target analysis, substantially expanding the chemical space that can be explored in environmental samples. In addition, non-target HRMS approaches for the comprehensive molecular characterization of dissolved organic matter (DOM) will be presented, illustrating how these methods can reveal previously uncharacterized fractions of natural and anthropogenic organic mixtures in aquatic systems.

At the same time, the presentation will critically discuss the current challenges and limitations of LC-HRMS-based workflows. These include issues related to data complexity and dimensionality, compound annotation uncertainty, limited availability and quality of spectral libraries, false positives and negatives in suspect screening, and the lack of harmonized and reproducible data processing pipelines. Particular attention will also be given to the specific challenges associated with DOM analysis, including its intrinsic heterogeneity and the difficulty of assigning structural information to thousands of unresolved features. The importance of quality assurance, transparent reporting, and methodological standardization will also be addressed.

Analytical workflows for suspect and non-target screening will be presented, illustrating case studies involving different environmental matrices, including domestic wastewater, lake water, and urban runoff, to demonstrate the applicability of these approaches to real-world complex mixtures.

Overall, this presentation will showcase how LC-HRMS-based methodologies are advancing environmental monitoring towards more holistic and informative assessments of chemical contamination and organic matter complexity, while also highlighting the critical methodological challenges that must be addressed to fully realize their potential.

Speaker: Prof. Mira Petrovic (Catalan Institute for Water Research (ICRA))

11:30 → 12:00 Life electric: from extracellular electron transfer to waste-to-value technologies

Life is fundamentally based on electrochemistry: in respiration, electrons from the oxidation of substrates are transferred to terminal electron acceptors, generating electrochemical gradients that drive ATP synthesis. Electrogenic microorganisms extend this principle beyond the cell membrane by transferring metabolic electrons to extracellular minerals or solid electrodes. This extracellular electron transfer forms the basis of microbial electrochemistry and enables the direct coupling of microbial metabolism to electrochemical systems.

In this talk, I will introduce the basic principles of microbial electrochemical technologies, with a focus on microbial fuel cells. Starting from microbial respiration and electron transfer in organisms such as Geobacter sulfurreducens, I will show how electroactive biofilms can be cultivated on electrodes and studied using electrochemical and in operando techniques.

Building on these fundamentals, the talk will discuss how microbial electrochemical technologies can contribute to sustainable water, energy, and material cycles1. Wastewater is not merely a stream to be treated, but a large resource containing chemical energy, nutrients, and reusable water. Microbial fuel cells can convert part of this energy into electricity, while related systems may produce hydrogen or methane and support nutrient recovery, sensing, and decentralized sanitation.

Finally, I will critically address the challenges that still limit practical implementation, including scale-up, internal resistance, electrode materials, complex wastewater composition, long-term stability, and economic viability. Rather than replacing established treatment processes, microbial electrochemical technologies may find their future in targeted integration into circular, resource-oriented wastewater treatment schemes.

Speaker: Uwe Schröder

12:00 → 12:30 One Framework, Many Insights: A Unified Vision Of Voltammetry

Electrochemistry is far more than corrosion and batteries, it is embedded in entire life on Earth and in our environment.1 Breathing involves electrochemical oxygen reduction, while cellular energy production via Adenosine Triphosphate arises from electron-transfer reactions in the Mitochondrial Electron Transport Chain. While the Membrane Potential governs cellular communication, redox enzymes drive biochemical transformations, and ion transport sustains homeostasis. Drug action is also rooted in electrochemical interactions, highlighting electrochemistry as a universal language of charge transfer and energy conversion.
Voltammetry is recognized as the most prominent electrochemical technique and it is often seen as indispensable tool in modern laboratories, enabling direct probing of electron-transfer processes through current–potential measurements.2 It has provided fundamental mechanistic insights into various chemical and biochemical systems, allowing kinetic, thermodynamic, and quantitative analysis, with its importance reflected in several Nobel Prize in Chemistry recognitions.
Since the charge transfer is involved in vast majority of chemical and biological processes,3 voltammetry serves as a unifying platform across chemistry, pharmacy, biomedicine, physics, and environmental sciences. While voltammetry is easily achievable experimental technique, interpretation of voltammetric results often requires rigorous theoretical models.
This talk presents voltammetry as a unified framework addressing phenomena related to charge and mass transfer, and many other aspects such as adsorption, coupled chemical reactions, drug–drug interactions, nano-electrochemistry, and energy systems such as biofuel cells. By integrating experiments with theory, voltammetry emerges as one of the most versatile techniques, offering a unique perspective on electrochemical phenomena.

Speaker: Rubin Gulaboski (Faculty of Medical Sciences, Goce Delcev University, Stip, Macedonia)

13:30 → 16:45 Oral Presentations B

13:30 LC-ESI-MS/MS DETERMINATION OF POLYPHENOLS IN KRATOŠIJA WINE

Polyphenols are important compounds in red wine that determine the color, stability, sensory characteristics, astringency and bitterness as well as stabilizing wine during the aging period. This study is focused on the determination of polyphenols, including flavonoids (anthocyanins, pyranoanthocyanins, flavonols and flavan-3-ols) and non-flavonoids (phenolic acids and stilbenes), in red Kratošija wines, applying HPLC-ESI-MS/MS method. The wines were produced using two commercial yeasts for fermentation in order to study the effect of the yeast on the phenolic compounds profile and content. The chromatographic separation of compounds was performed by using a mobile phase consisting of acetonitrile as solvent A and formic acid (pH 2.8) as solvent B, in a gradient mode, as follows: 0-3 min 10% A, 3-10 min 20% A, 10-15 min 25% A, 15-31 min 90% A and 31-50 min 100% A. Wine samples were injected directly into the HPLC system, after filtration through 0.20 μm polyester membrane, using Kinetex C18 column (100 x 2.1 mm, 2.6 µm) for separation. The accuracy and precision of the method were evaluated and the LOD, LOQ and correlation coefficient were determined. The method showed satisfactory characteristics for the analysis of phenolic compounds in red wine. In the wine samples, analytes were identified based on the knowledge of their fragmentation pathway and by comparing the retention times with their reference standards. Quantification was performed by constructing calibration curves for the available standards and for the other compounds, relative amount was calculated based on the peak area calculation from the appropriate ion peak chromatogram. It was found that the content of polyphenolic compounds was significantly influenced by the yeast strain suggesting that the phenolic profile of wine can be modulated through the appropriate selection of yeast for fermentation.

Speaker: Dr Violeta Ivanova-Petropulos (Faculty of Agriculture, Goce Delcev University, Stip)

13:45 Natural Deep Eutectic Solvents as Sustainable Extraction Media for Bioactive Compounds from Medicinal and Endemic Plants of Kosovo

This study studies the extraction of bioactive compounds from selected medicinal and endemic plant species of Kosovo (Thymus praecox, Urtica dioica, Juniperus communis, Hypericum perforatum, Campanula albanica, and Xeranthemum annuum) using Natural Deep Eutectic Solvents (NADES) as sustainable extraction media. The research aims to evaluate the efficiency of NADES in recovering antioxidant-rich compounds, including phenolics and flavonoids, and to compare their performance with conventional organic solvents. Extracts will be characterized through phytochemical analyses and assessed for their antioxidant activity. The study will also examine the ability of NADES to preserve and stabilize bioactive compounds during extraction. The results are expected to contribute to the advancement of green extraction technologies and support the development of natural products for pharmaceutical, cosmetic, and functional food applications.

Speaker: Flaka Doli (Department of Chemistry, Faculty of Mathematical and Natural Sciences, University of Prishtina, Kosovo)

14:00 EVALUATION OF TOTAL POLYPHENOLIC CONTENT AND ANTIOXIDANT CAPACITY (DPPH, ABTS, AND FRAP) OF EXTRACTS FROM DIFFERENT BEAN VARIETIES

Beans are an important source of nutrients and bioactive compounds, particularly phenolic compounds, which contribute to their antioxidant properties and potential health benefits. The content of these compounds and their antioxidant potential may vary among different bean varieties, making their comparative evaluation important for nutritional and functional food research. The aim of this study was to comparatively evaluate the total polyphenol content (TPC) and antioxidant activity of bean extracts obtained from different bean varieties. Bean samples were extracted with 70% ethanol using ultrasound-assisted extraction for 30 minutes. The TPC of the extracts was determined using the Folin-Ciocâlteu method and expressed as milligrams of gallic acid equivalents per gram of dry weight (mg GAE/g DW). Antioxidant activity was evaluated using three spectrophotometric assays: DPPH radical scavenging activity, ABTS radical cation decolorization assay, and ferric reducing antioxidant power (FRAP)1. In addition, correlation analysis was performed to investigate the relationship between total polyphenol content and antioxidant activity. The results revealed differences in TPC and antioxidant activity among the investigated bean extracts. A strong positive correlation was observed between TPC and the antioxidant assays, indicating that phenolic compounds contribute substantially to the overall antioxidant potential of the extracts. The findings of this study contribute to a better understanding of the antioxidant characteristics of bean extracts and support their potential application as natural sources of bioactive compounds in functional foods2.

Speaker: Prof. Mirjana S. Jankulovska (Ss. Cyril and Methodius University in Skopje, Faculty of Agricultural Sciences and Food - Skopje)

14:15 Transformation Pathways of Perfluorooctanoic Acid under Photocatalytic and Bioelectrochemical Conditions: Insights from Target and Non-Target Analysis

Perfluorooctanoic acid (PFOA) is one of the most persistent per- and polyfluoroalkyl substances (PFAS), requiring advanced treatment technologies and reliable analytical approaches to elucidate transformation mechanisms. In this study, photocatalytic degradation using immobilized rGO-doped TiO₂ coatings and long-term bioelectrochemical treatment in sediment microbial fuel cells (MFCs) were comparatively investigated.
Targeted LC-MS/MS analysis revealed progressive chain shortening of PFOA and formation of shorter-chain perfluoroalkyl carboxylic acids in both systems. Photocatalytic treatment produced perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), accompanied by fluoride release, while high-resolution mass spectrometry confirmed additional intermediates.1 Ten months of MFC operation resulted in a 94.9 % decrease in extractable PFOA, with PFHpA and PFHxA detected as major products.2
The results demonstrate that both abiotic and bioelectrochemical systems promote stepwise shortening of the fluorinated carbon chain, whereas complete mineralization could not be confirmed. The study highlights the importance of combining targeted and non-target analytical approaches to distinguish apparent removal from actual degradation and improve understanding of PFAS transformation pathways.

Speaker: Vladimir Beškoski (University of Belgrade - Faculty of Chemistry)

14:30 BIOMARKERS OF EXPOSURE TO POLYCYCLIC AROMATIC HYDROCARBONS IN WASTEWATER-BASED EPIDEMIOLOGY

Polycyclic aromatic hydrocarbons (PAHs) are a group of compounds that belong to a group of “emerging contaminants”. The presence of PAHs in the environment is widely detected. It has been confirmed that these compounds may have negative impact on organisms. Studies have shown that PAHs are suspected to be mutagenic, teratogenic and cancerogenic. One of the groups of compounds that are biomarkers of exposure to PAHs are their hydroxyl derivatives (OH-PAHs). According to the studies, OH-PAHs can also negatively influence on organisms and environment. Therefore, it is crucial to monitor the presence and concentration of PAHs, as well as OH-PAHs. One of the most common biomarkers of PAHs is 1-hydroxypyrene.
The role of biomarkers is especially important in the case of the wastewater-based epidemiology. Wastewater-based epidemiology is a special approach that allow us to obtain information about health risk by measuring the concentration of different kinds of chemical and biological markers. This approach is based on the assumption that biomarkers are metabolites of different kind of organic compounds, that are excreted by human in urine and enter wastewater treatment plant. Given the fact that polycyclic aromatic hydrocarbons have definitely negative impact on human lives, determination of the concentration of their biomarkers seems to become very important issue. Studies have shown that one of the most accurate biomarkers of polycyclic aromatic hydrocarbons are their hydroxyl derivatives.
This work focused on determination of hydroxyl derivatives of PAHs in the wastewater samples. The tested compounds were: naphthols, fluorenols, phenanthrenols, 1-hydroxypyrene and 3-hydroxybenzo(a)pyrene. The samples were collected in wastewater treatment plant in Krakow, Poland. The concentration of OH-PAHs was measured using ultra performance liquid chromatography (UHPLC) coupled with tandem mass spectrometry.

Speaker: Prof. Katarzyna Styszko (AGH Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie)

14:45 EVALUATION OF DIFFERENT SOLVENTS FOR LIQUID–LIQUID EXTRACTION OF SELECTED PESTICIDE RESIDUES FROM WATER SAMPLES

The determination of pesticide residues in water requires efficient sample preparation procedures1 to ensure reliable analytical results. Therefore, the aim of this study was to evaluate the extraction efficiency of different organic solvents for the liquid–liquid extraction (LLE) of 2,4-dichlorophenoxyacetic acid (2,4-D), atrazine, malathion, fenitrothion and parathion from water samples.
Fortified distilled water samples containing selected pesticides were used as model samples. Three concentration levels were investigated for each pesticide, and for each concentration level, four samples (n = 4) were prepared. Liquid–liquid extraction was performed using dichloromethane, diethyl ether, petroleum benzine and a mixture of n-hexane and acetone (4:1, V/V). The extracts were analyzed by reversed-phase high-performance liquid chromatography (RP-HPLC) method and the extraction efficiency was evaluated through recovery values.
Among the investigated solvents, dichloromethane exhibited the highest overall extraction efficiency, providing recoveries between 96.09 % and 106.52 % for all analytes except malathion, for which a lower but still satisfactory recovery of 78.89 % was obtained. Diethyl ether also showed good performance, with recoveries ranging from 90.73 % to 106.99 %, except for malathion (71.95 %). Petroleum benzine proved unsuitable for the extraction of 2,4-D (only 5.24 % recovery), while recoveries for the remaining pesticides ranged from 57.27 % to 83.18 %. The n-hexane/acetone mixture (4:1, V/V) demonstrated high extraction efficiency for malathion, fenitrothion and parathion (96.59 % – 105.78 %), moderate efficiency for 2,4-D (84.17 %), and lower efficiency for atrazine (74.06 %).
The overall extraction efficiency decreased in the following order: dichloromethane > diethyl ether > n-hexane/acetone (4:1, V/V) > petroleum benzine. The obtained results indicate that dichloromethane is the most suitable extraction solvent for the investigated pesticides and provide a basis for future application of the proposed procedure to environmental, drinking and irrigation water analysis.

Speaker: Prof. Lenche Velkoska-Markovska

15:00 Coffee Break

15:30 COMPARATIVE EVALUATION OF THREE VALIDATED RP-HPLC METHODS FOR ASSESSING LIQUID–LIQUID EXTRACTION EFFICIENCY OF SELECTED PESTICIDES

Reliable evaluation of extraction efficiency is essential for the development of analytical procedures for pesticide residue determination in water. This study compares the applicability of three previously validated RP-HPLC methods for assessing the efficiency of liquid–liquid extraction (LLE) of 2,4-dichlorophenoxyacetic acid (2,4-D), atrazine, malathion, fenitrothion and parathion from water samples.
Fortified distilled water samples containing selected pesticides at three concentration levels were subjected to LLE using dichloromethane, diethyl ether, petroleum benzine and a mixture of n-hexane and acetone (4:1, V/V). The extracts were analyzed using three validated RP-HPLC methods1,2 employing RP-8 columns of different dimensions under optimized isocratic chromatographic conditions.
All three methods provided satisfactory separation of the investigated pesticides, with resolution values for the closest eluting peaks exceeding 1.5. Although the shortest column reduced the analysis time from approximately 10 to 4 min, it maintained chromatographic performance and analytical sensitivity comparable to those of the longer columns. Furthermore, all three methods provided similar recovery values and identical ranking of extraction solvent efficiency, identifying dichloromethane as the most efficient solvent, followed by diethyl ether, n-hexane/acetone (4:1, V/V) and petroleum benzine.
The results demonstrate that all three validated RP-HPLC methods are suitable for evaluating LLE efficiency. Their consistent analytical performance confirms the reliability of the proposed approach, while the shortest RP-8 column offers a practical advantage for routine analysis owing to its substantially shorter analysis time.

Speaker: Lenche Velkoska-Markovska (“Ss. Cyril and Methodius” University in Skopje, Faculty of Agricultural Sciences and Food - Skopje, Republic of North Macedonia)

15:45 Comparison of ICP-AES and XRF techniques for the analysis of chemical elements in moss samples from Kosovo

The aim of this research was to analyze the concentrations of some chemical elements (Al, Ca, Cu, Fe, K, Mn, P and Zn) in moss samples, using two different analytical techniques (ICP-AES and XRF), to compare their compatibility, correlation and suitability1,2. The mean and median values for some chemical elements (Ca, K and Mn) were higher in the ICP-AES method, compared to XRF, while for the chemical elements (Fe, P and Cu) these values are very close from both analytical techniques. The comparison between ICP-AES and XRF measurements demonstrates generally strong agreement for most elements. Very strong positive correlations were observed for Al (r=0.885), Fe (r=0.899), Mn (r=0.837), P (0.842) and Zn (r=0.977), indicating that both analytical techniques capture similar spatial and concentration trends among moss samples3. The moderate correlations between analytical techniques were for Ca (r=0.701) and K (r=0.680). The appearance of copper with very weak correlation (r=0.012), suggests that the concentrations were close to the limits of analytical detection and are therefore more affected by analytical uncertainty. In general, both analytical methods show good correlation with each other for most chemical elements, as XRF offers comparable trends with the advantage of rapid and non-destructive analysis of samples, while ICP-AES remains preferable when maximum analytical accuracy is required.

Keywords: ICP-AES, XRF, moss, Kosovo, Pearson correlation.
References:
1. Fedeli, R.; Di Lella, L. A.; Loppi, S. Suitability of XRF for routine analysis of multi-elemental composition: A multi-standard verification. Methods and Protocols 2024, 7(4), 53.
2. Al Maliki, A.; Al-lami, A. K.; Hussain, H. M.; Al-Ansari, N. Comparison between inductively coupled plasma and X-ray fluorescence performance for Pb analysis in environmental soil samples. Environmental Earth Sciences, 2017, 76(12), 433.
3. Dreshaj-Lecaj, E.; Haskaj, A.; Paçarizi, M. Pollution indicators of heavy metals in the sediments of the Lepenc river in Kosovo. Environment Protection Engineering, 2024, 50(3), 77-87.

Speaker: Prof. Musaj Paçarizi (Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Prishtina “Hasan Prishtina”)

16:00 VALIDATED ANALYTICAL APPROACH FOR SOIL CARBON MONITORING: MULTI-CROP EVIDENCE FROM CARBON FARMING SYSTEMS

Reliable and affordable determination of soil organic carbon (SOC) is essential for evaluating carbon-farming practices and developing scalable soil-carbon monitoring systems. This study aimed to validate an effective analytical approach for routine SOC determination and demonstrate its applicability through multi-crop field monitoring under carbon-farming conditions in North Macedonia.
The classical Walkley-Black method and its spectrophotometric modification were evaluated through linearity, precision, accuracy, repeatability, reproducibility, and analysis of reference soil material. The titrimetric method demonstrated excellent linearity over 0.3-3.0% OC (R² = 0.999), while spectrophotometric determination of Cr³⁺ at 600 nm showed similarly strong linearity (R² = 0.9996). Validation using reference soil produced OC values of 1.75% by titrimetric WB and 1.78% by spectrophotometric determination, both within the accepted reference interval (1.72-2.14%), demonstrating good analytical agreement and supporting the applicability of the rapid spectrophotometric approach for routine monitoring.
The analytical approach was further applied to track soil-carbon dynamics under carbon-farming (CF) and conventional management systems (CMS) across corn, sunflower, barley, and chickpea. Under CF, soil C increased from 1.20 to 1.89% in corn, 1.19 to 1.42% in sunflower, 1.25 to 1.68% in barley, and 1.18 to 1.57% in chickpea. In contrast, CMS showed consistent depletion, reaching final values of 0.93, 0.76, 0.89, and 0.91%, respectively. Final carbon concentrations under CF were approximately 73.1-103% higher than under corresponding conventional systems.
The combination of analytical validation and field application demonstrates that validated, cost-effective carbon determination can provide sufficient analytical performance for repeated soil monitoring. Such approaches could substantially increase monitoring frequency and spatial coverage while supporting future measurement, reporting and verification (MRV) frameworks for carbon farming.

Keywords: soil organic carbon, method validation, Walkley-Black, spectrophotometry, carbon farming.

Speaker: Biljana Balabanova (Faculty of Agriculture, Goce Delcev University)

16:15 The assessment of metal content to Cuercus Petraea wood ash, properties and the impact in air quality

In most parts of Kosova during winter time, in many living spaces, by choice, woods are used for heating. Apart from warming atmosphere, wood burning affect air quality, inner and outer atmosphere. This is the main reason to this study.
Cuercus Petraea, sessile oak or cornish oak wood ash is chosen as sample of research. Atomic absorption spectrometry is used as method. 20 wood ash samples were collected from home fire places, day after burning.
Measurements detected metals Fe, Zn, Cu, Pb, Cd, Ni, Cr in different concentrations. Cu, Cd, Cr in smaller concentrations. Ranges from 2 – 2, 62 mg/kg for Cu, Cr and Cd were in much lower concentrations, Cr in range from 0.01 – 0.03 mg/kg, while Cd concentrations in range from 0.08 – 0.26 mg/kg. Fe, Zn and Ni concentrations were much higher; from 180.55 – 520 mg/kg for Fe; 35.24- 65.9 mg/kg for Zn and 38.4 – 68.5 mg/kg for Ni, all in dry weight.
Other parameters: LOI (0.1 - 9.5%), pH (10.2 – 10.79), EC (3.18 – 9.61), and total alkalinity (240 – 436.8 mg/L), % DM (81 – 98), % Ash (83 – 98.9) and % OM (0.01 – 0.33) are also different regardless the same type tree wood ash.

Speaker: Prof. Albana Mehmeti (University of Prishtina)

16:30 Unravelling the Energy–Air Pollution–Climate–Health Nexus in Kosovo: Implications for Sustainable Energy Transition and Public Health

Unravelling the Energy–Air Pollution–Climate–Health Nexus in Kosovo: Implications for Sustainable Energy Transition and Public Health

Janina Çeku1, Vesa Salihu1, Vlere Krasniqi1, Majlinda Daci1
e-mail: janina.ceku@student.uni-pr.edu

1Department of Chemistry, Faculty of Mathematical and Natural Sciences, University of Prishtina, Republic of Kosovo

Kosovo represents a unique case for investigating the interconnections between energy systems, air pollution, climate-related factors, and public health outcomes due to its high dependence on lignite-based electricity generation, widespread use of solid fuels for household heating, and persistent air quality challenges.
This study aims to examine the complex interactions between energy production and consumption patterns, air pollutant emissions, climate-related conditions, and population health through an integrated nexus approach. Specifically, the research investigates the contribution of electricity generation, household heating, biomass use, and transport to ambient air pollution; assesses the influence of meteorological and climate-related factors on pollution patterns; and evaluates the associations between air pollution exposure and respiratory and cardiovascular health outcomes. The conceptual framework links energy-related emissions of particulate matter (PM₂.₅), sulfur dioxide (SO₂), nitrogen oxides (NOₓ), and carbon dioxide (CO₂) with climate-related factors, including temperature inversions, heat waves, droughts, seasonal variability, and stagnant air conditions, which together influence air quality and human exposure.
Preliminary results indicate substantial seasonal and spatial variations in PM₂.₅ concentrations across Kosovo. In 2022, annual average PM₂.₅ concentrations reached 18.1 µg/m³ in Prishtina, 16.4 µg/m³ in Drenas, 20.4 µg/m³ in Mitrovica, and 20.1 µg/m³ in Obiliq, exceeding the World Health Organization annual guideline value of 5 µg/m³. Winter pollution episodes were particularly pronounced, with monthly average PM₂.₅ concentrations exceeding 30 µg/m³ in several locations and maximum hourly concentrations reaching 167.2 µg/m³ in Obiliq.
The findings are expected to provide evidence on the interconnected nature of energy use, climate variability, air pollution, and health impacts in Kosovo, highlighting the public health co- benefits of sustainable energy transition pathways. The study emphasizes the need for integrated energy–climate–health policies to support decarbonization, improve air quality, strengthen climate resilience, and protect population health.

Keywords: energy transition; air pollution; PM2.5; climate change; public health;lignite; sustainable development; energy–climate–health nexus.

Speaker: Janina Çeku (Student at the University of Prishtina)

13:30 → 16:45 Oral Presentations C

13:30 Possibility of Constructing 2T2D Correlation Maps from IR Reflectance Spectra and 2D Correlation Maps from Confocal Raman Spectra

IR Specular Reflectance (IR-SR) spectroscopy is an external reflectance technique widely used in the investigation of various materials. The IR light is specularly reflected, as described by the Fresnel equations, and contains information about the optical, dielectric, and vibrational properties of the material, which can be extracted using dispersion or Kramers–Kronig analysis. Particularly useful, however, is the application of IR-SR in the investigation of thin and ultrathin films. In the latter case (film thickness up to 100 nm), a simplification of the reflectance function can be introduced, whereby the reflectance function can be approximated as a reflectance–absorbance function; that is, the absorbance of the film can be evaluated through reflectance measurements. The reflectance–absorbance (IR-RA) spectrum, calculated from the ratio-reflectance (IR-RR) spectrum for a system consisting of soda-lime-silicate glass coated with an ultrathin siloxane film, can reveal the vibrational properties of the film, including the wavenumber positions and profiles of the IR bands, from which information on the assignment of the Si–O–Si vibrations can be obtained. To demonstrate, however, that this method provides reliable results, they must be verified using an independent method. For this purpose, the construction of two-trace two-dimensional correlation spectroscopy (2T2D-COS) maps from the originally recorded IR-SR spectra was proposed. The resulting maps, particularly the asynchronous maps, show peaks that correspond well to the band maxima observed in the IR-RA spectra of the film. It will be shown that this approach can be used not only for films with thicknesses close to 100 nm, but also for films only a few nanometers thick. The 2T2D-COS maps can also be constructed from IR-RA spectra, in which case they provide information on whether two films have the same structure. In addition to its application in IR reflectance spectroscopy, Raman spectroscopy of thin films can also be used to distinguish bands belonging to the glass substrate from those originating from the film. However, it remains unclear whether 2T2D-COS can be successfully applied when the intensities of the substrate and film bands change randomly and vary from one measurement to another, particularly in cases where spectral normalization is not possible. To address this problem, two-dimensional correlation spectroscopy (2D-COS) was applied to a series of Raman confocal spectra recorded from the same silane-modified glass sample at the same laser position. The measurements were performed on a thicker part of the film (≈1 μm), while the perturbation introduced was the position of the laser focus, i.e., the depth of measurement within the film. In this way, the asynchronous map made it possible to distinguish some of the overlapping bands and assign them either to the glass substrate or to the film.

Keywords: soda-lime-silicate glass; siloxane, IR Specular Reflectance; Raman spectroscopy; Two-trace two-dimensional correlation spectroscopy; Two-dimensional correlation spectroscopy

Speaker: Vladimir Ivanovski (Ss. Cyril and Methodius University in Skopje, Faculty of Natural Sciences and Mathematics, Institute of Chemistry, Arhimedova 5, Skopje, Macedonia)

13:45 TWO-DIMENSIONAL CORRELATION ANALYSIS OF FANO RESONANCE LINE SHAPES: DISCOVERING NEW SPECTROSCOPIC FINGERPRINTS

Fano-type resonance phenomena originate from quantum interference between excitations involving discrete and continuum states, giving rise to characteristic asymmetric spectral response profiles, which are highly sensitive to changes in resonance energy, linewidth, discrete-continuum coupling strength, and the surrounding environment. Such line shapes are ubiquitous in atomic, molecular and condensed-matter systems, particularly in plasmonic nanostructures and nanophotonic materials. Despite the considerable interest in these phenomena, disentangling subtle spectral variations and correlated changes of the Fano parameters remains rather challenging using conventional one-dimensional spectroscopic approaches.
In the present work, we employ several variants of two-dimensional correlation spectroscopy (2DCOS) to investigate the evolution of Fano resonance line shapes under different external perturbations. Dynamic spectra generated through systematic variations of the asymmetry parameter, resonance energy, linewidth and coupling strength are used to construct the generalized synchronous and asynchronous correlation maps. Characteristic cross-peak patterns are identified, enabling discrimination between frequency shifts, linewidth variations and changes in spectral asymmetry, and allowing the construction of a corresponding library of 2DCOS fingerprints. We further establish correlations between the physical mechanisms governing the Fano line-shape evolution and the topology of the corresponding two-dimensional correlation patterns. In addition to the generalized 2DCOS approach, we present a detailed analysis based on autocorrelation moving window two-dimensional correlation spectroscopy (MW-2DCOS) and perturbation-correlation MW-2DCOS (PC-MW-2DCOS) applied to the same datasets.
The simulation results are compared with experimental data for plasmonic semiconductor quantum dots, in which pronounced plasmon – exciton coupling gives rise to distinct Fano-type features in both optical absorption and photoluminescence spectra.
These results establish 2DCOS as a sensitive tool for decoding the dynamics of Fano resonances and for elucidating the mechanisms underlying their spectral evolution, as well as probing e.g. plasmon-exciton interactions in strongly coupled nanoscale systems.

Keywords: Fano resonance, Fano line shapes, plasmonic semiconductor quantum dots, two-dimensional correlation spectroscopy (2DCOS), plasmon-exciton coupling, optical absorption, photoluminescence.

Speaker: Ljupcho Pejov (Institute of Chemistry, Faculty of Natural Sciences and Mathematics, SS Cyril and Methodius University, 1000 Skopje, Republic of North Macedonia)

14:00 Why the Peak Is Not Enough: Univariate Calibration Beyond the Beer–Lambert Approximation

In spectrophotometric analysis, univariate calibration is often based on the intuitive assumption that the maximum of an absorption band provides the best analytical signal. This practice is closely connected to the Beer–Lambert relation, which suggests a linear dependence of absorbance on concentration and makes the most intense spectral position appear especially attractive because of its high sensitivity. However, peak height alone is not a reliable criterion for optimal calibration.

This lecture examines why the best univariate calibration point is frequently not located at the peak maximum. The discussion is illustrated using UV-Vis spectra of methyl orange and infrared spectra of thermodynamically ideal binary mixtures, including benzene–toluene, benzene–cyclohexane, and benzene–carbon tetrachloride. By comparing calibration performance across spectral positions and relating prediction errors to sensitivity, spectral separation, and curvature of the concentration-dependent response, it becomes clear that band flanks or apparently less prominent regions can outperform the absorbance maximum

Speaker: Thomas Mayerhöfer (Leibniz Institute of Photonic Technology)

14:15 Investigation of Electroactive Geobacter sulfurreducens: Insights from Square-Wave Voltammetry and Cyclic Voltammetry

Understanding electroactive biofilms is essential to advance the development of microbial fuel cells (MFCs), biological wastewater treatment, and to comprehend the bacterial communication pathways. Although decades of research have investigated electroactive bacteria (EAB), particularly G. sulfurreducens and S. oneidensis, the exact electron transfer mechanisms between EAB and electrodes remain poorly understood.1
This presentation highlights square-wave voltammetry (SWV) as a powerful, yet often-overlooked technique, to investigate early-stage biofilm formation and elucidate these electron transfer pathways (Fig. 1). Furthermore, these results are contextualized with traditional cyclic voltammetry.2 This comparative analysis provides new insights into how biofilms exchange electrons with the electrode interface.

Speaker: Franz Glaubitz (University of Greifswald)

14:30 Surface interaction of Ni based electrocatalyst with hydrogen peroxide

In this study, non-stoichiometric Ni–O thin films were synthesized by magnetron sputtering, enabling precise control over their morphology independently of the chemical composition. X-ray diffraction indicated the presence of crystalline Ni(111) planes, while Raman confirmed amorphous nickel oxide. Samples with the various amount of crystalline Ni were grown. X-ray photoelectron spectroscopy further revealed a mixture of metallic Ni and partially oxidized Ni–O species. Electrochemical analysis demonstrated that the thin films characterized by highly abundant Ni(111) planes exhibit catalytic activity for H2O2 detection, with the current density of –1.64 × 10⁻⁴ A/cm². To gain deeper insight into the underlying mechanisms, density functional theory calculations were performed, showing that metallic sites on Ni(111) offer stronger interaction for OH groups than amorphous NiO, with average adsorption energies of –3.76 and –1.86 eV, respectively. The simulations also indicated that OH groups from H2O2 preferentially dock onto bridge sites of Ni(111). These findings highlight the significant potential of non-stoichiometric Ni–O systems for electrochemical sensing applications and provide valuable understanding of H2O2 interactions with oxides.

Speaker: Nabi Ullah (University of Lodz)

14:45 THERMODYNAMIC FOUNDATIONS OF ACTIVITY COEFFICIENTS OF ELECTROLYTES IN ELECTROSTATIC THEORIES

THERMODYNAMIC FOUNDATIONS OF ACTIVITY COEFFICIENTS OF ELECTROLYTES IN ELECTROSTATIC THEORIES

Janez Cerar1
e-mail: janez.cerar@fkkt.uni-lj.si

1Faculty of Chemistry and Chemical Technology, University of Ljubljana,
Večna pot 113, SI-1000 Ljubljana, Slovenia

Activity coefficients provide a measure of the non-ideality introduced by a species in a system. In electrolyte solutions, strong electrostatic interactions often cause ionic activity coefficients to deviate substantially from unity, even at low concentrations. Although the century-old Debye–Hückel theory1 successfully predicts activity coefficients in dilute solutions, only recently has a thermodynamic decomposition of these contributions been achieved2.
Within the Debye–Hückel framework, it can be demonstrated that the energetic contributions of induced repulsive electrostatic interactions and entropy are each exactly half the magnitude—but opposite in sign—to that of the direct attractive electrostatic interaction between the central ion and its ionic atmosphere. This decomposition not only deepens our understanding of how ions influence their surroundings but also establishes a direct link between activity coefficients and the microscopic behaviour of individual ions.
This work explores potential extensions of the approach to other electrostatic theories, including the non-linear Poisson–Boltzmann equation, the Hypernetted Chain (HNC) equation, and the incorporation of non-Coulombic terms. Furthermore, its applicability to polyelectrolyte solutions—of both spherical and cylindrical symmetry—is considered. Finally, the approach enables the validation of such thermodynamic dissections, ensuring consistency across theoretical frameworks.

Keywords: electrolyte solutions, entropy, attractive interactions, induced repulsive interactions.

References:
(1) Debye, P.; Hückel, E. Zur Theorie der Elektrolyte. I. Gefrierpunktserniedrigung
und verwandte Erscheinungen. Phys. Z., 1923, 24, 185-206.
(2) Cerar, J. Thermodynamic decomposition of Debye–Hückel activity coefficients: resolving attractive, repulsive, and entropic components. Phys. Chem. Chem. Phys., 2026, 28, 16841-16850.

Speaker: Janez Cerar (Faculty of Chemistry and Chemical Technology, University of Ljubljana, Slovenia)

15:00 Coffee Break

15:30 An Analysis of Systems Thinking Skills in Chemistry Education Using a Bibliometric Approach

Chemistry education has historically developed through a reductionist approach focused on molecular structures, formulas, and reaction mechanisms. Although this approach has made significant contributions to the production of scientific knowledge and technological advancement, it is not sufficient on its own to address complex problems such as climate change, pollution, resource depletion, and sustainability. Therefore, chemistry education needs to be reconceptualized through a holistic approach that considers chemical processes in relation to social, economic, and environmental systems. In this context, systems thinking has emerged as an important approach for understanding the dynamic relationships among the components of complex structures, feedback loops, and the emergent properties of a system as a whole. Accordingly, it is important to transform chemistry curricula on the basis of systems thinking and to support students in developing systems thinking skills. The aim of this study is to examine the development, main trends, and research gaps in academic studies on systems thinking and related skills in the chemistry education literature through bibliometric analysis. Within this scope, the study was conducted in the Web of Science (WoS) database using the keywords (("systems thinking" OR "system thinking") AND ("skill" OR "skills") AND ("chemistry")), and 108 sources were retrieved. Studies outside the Education Educational Research category and book chapters were excluded from the dataset, and the analyses were conducted based on 76 articles. The study examined publication and citation trends by year, the productivity and collaboration levels of countries, and the shared citation network. The findings indicate a marked increase in the number of publications and citations after 2019, suggesting that systems thinking skills have become an emerging paradigm in chemistry education. Publication and collaboration analyses by country show that the USA, Canada, Israel, and England are the countries contributing most substantially to the field, whereas Turkey’s contribution remains relatively limited. Keyword analysis reveals that “systems thinking” is located at the conceptual center of the field and that this concept reflects the current direction of the field through its strong connections with “sustainability” and “green chemistry”. Co-citation analysis shows that the study by Orgill et al. (2019) is the most cited study in the field.1 In conclusion, systems thinking skills can be considered an emerging research area in chemistry education, and further studies are needed in this field.

Speaker: Mr Ali OZLUSOY (Dokuz Eylül University)

15:45 The Effect of Chemistry-based STEM Activities on High School Students’ Argumentation Quality

The purpose of this study is to investigate the effect of chemistry-based STEM activities on students’ argumentation quality. The study involved 22 tenth graders in 2023–2024. Over 10 weeks, three STEM activities were implemented, each incorporating relevant learning outcomes from the chemistry topics of “Mixtures,” “Acids, Bases and Salts,” and “Chemistry Everywhere.” Students followed Hynes et al.’s (2011) nine-step Engineering Design Process and answered 16 open-ended questions across its steps. However, within the scope of this study, we focused on the responses to the five questions corresponding to the first two steps of the Engineering Design Process. The questions were written on Padlet platform and asked students to response them individually on Padlet as a homework study. The responses were analyzed using the rubric developed by Venville and Dawson (2010), which includes levels representing argumentation quality. For instance, while Level 1 includes only a claim, Level 3 includes arguments in which students use a claim, data or warrants and backing. The responses were coded independently by two researchers, and disagreements were resolved through discussion. The findings showed that in Activity 1, most individual written arguments were at Level 1, whereas fewer were at Levels 2 and 3. In Activity 2, the distribution of argumentation levels was 163, 74, and 3, respectively. In Activity 3, the corresponding frequencies were 128, 79, and 7. Although Level 1 arguments were predominant across all three activities, the frequencies of Level 2 and Level 3 arguments increased from Activity 1 to Activity 3. This finding indicates that students gradually moved beyond merely presenting claims and began to justify and support their arguments with evidence. The improvement in argumentation quality suggests that chemistry-based STEM activities may enhance students’ academic achievement. Therefore, it is recommended that such activities be implemented more widely in chemistry education.

Keywords: STEM, Chemistry Education, Argumentation

Speaker: AYBUKE PABUCCU AKIS (Dokuz Eylul University)

13:30 → 16:45 Oral Presentations S

13:30 Synthesis of silver nanospirals

The unusual geometry of spiral nanocrystals gives rise to unique optical, electronic, and mechanical properties. Spiral growth of noble metals was demonstrated for gold decades ago but no information about silver nanospirals was reported. Here present novel approach for preparation of silver nanospirals with yields of over 90%, based on application of 3-mercaptopropionic acid (MPA) ligand. Addition of H2O2 results in formation of different morphologies of silver such as dendrites, nanoribbons, nanospirals or nanoflowers, depending on MPA concentration. Formation of such variety of structures is result of MPA coverage-dependent conformational change and decrease of total nanoparticle surface area during H2O2 addition, causing sudden change from repulsion to attraction of silver nanoparticles. Consequently, rapid 2D oriented assembly launches diffusion-limited auto-accelerated process. When random dendrite arms overlap due to mismatch caused by a rapid growth, this represents the point of spiral formation. Silver morphology can be fine-tuned via MPA/silver nanoparticles ratio, providing therefore a bottom-up route for twisted nanocrystal synthesis within minutes.

Speaker: ALES PODGORNIK (Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 133, Ljubljana, Slovenia)

13:45 Sustainable Construction Materials through Alkali Activation of Fly Ash and Metakaolin

Alkali-activated composites based on fly ash (FA) and metakaolin (MK) were designed as sustainable low-carbon construction materials. The fly ash was mechanically activated in a planetary mill for 20 min to enhance its reactivity, while metakaolin was produced by the thermal treatment of kaolin at 700 °C for 2 h. Sodium hydroxide and sodium silicate solutions were used as alkaline activators. The curing regime consisted of 24 h at 50 °C, followed by curing at room temperature up to 28 days. Different alkali-activated composites were designed using as-received fly ash, mechanically activated fly ash, and mechanically activated fly ash with the addition of metakaolin at 10, 25, and 50 wt.%. The raw materials and the synthesized alkali-activated composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). In addition, bulk density, capillary water absorption, and compressive strength were determined for all alkali-activated composites. The physical and mechanical properties of the alkali-activated composites were evaluated after 28 days of curing. The bulk density of the hardened products ranged from 1.05 to 1.50 g/cm³, depending on the precursor composition and metakaolin content. The compressive strength varied between 8 and 32 MPa. Among the investigated formulations, the composite containing 25 wt.% metakaolin exhibited the highest compressive strength (32 MPa) and the most compact microstructure, indicating a synergy between mechanically activated fly ash and metakaolin. The results demonstrate that the combined use of mechanically activated fly ash and metakaolin is an effective approach for producing alkali-activated materials with enhanced performance. The study supports the green transition and the principles of the circular economy by valorizing fly ash, an industrial by-product, as a secondary raw material for the design of sustainable low-carbon construction materials.

Speaker: Emilija Fidanchevski (Prof.)

14:00 SUSTAINABLE GEOPOLYMER COMPOSITES INCORPORATING MUNICIPAL CONTAINER

Ordinary Portland cement (OPC) production significantly contributes to global greenhouse gas emissions . Geopolymers synthesized from metakaolin offer an eco-friendly alternative, though unreinforced matrices can exhibit microstructural brittleness under load . Incorporating fiber reinforcement enhances mechanical performance and structural behavior . This study analyzed the effect of fibers derived from recycled municipal solid waste containers on the compressive strength of a geopolymer matrix composed of metakaolin and sand.
Geopolymer composites were synthesized using metakaolin and sand (1:1 mass ratio) activated with a 10 M NaOH and aqueous sodium silicate solution. Shredded white or green container waste fibers were incorporated at 5% and 7% volume fractions, and mechanical testing was performed after 28 days of curing. Two series of geopolymer samples were tested: fibers of a white waste container and fibers of a green waste container. In the white container series, adding 5 vol.% fibers increased compressive strength from 35.0 MPa (reference) to 37.5 MPa, while a 7 vol.% content produced a 14% enhancement – 39,9 MPa. For the green container series, a 7 vol.% fiber content successfully raised compressive strength by 4% compared to the reference sample (27.9 MPa).
The test results indicate that addition of shredded waste from waste containers effectively improves the compressive strength of metakaolin-based geopolymers, confirming the potential for recycling municipal plastics from containers to provide functional reinforcement for sustainable building materials.

Keywords: geopolymers, fiber reinforcement, waste fibers, sustainable materials

Literature:
1. Jwaida, Z.; Dulaimi, A.; Mashaan, N.; Othuman Mydin, M.A. Geopolymers: The Green Alternative to Traditional Materials for Engineering Applications. Infrastructures 2023, 8, 98.
2. Rajendran S.; Palani G.; Veerasimman A et al. Enhancing carbon fibercomposites with fish scale biochar for superior strength and environ-mental sustainability. Clean Eng Technol 2025, 27:100996
3. Korniejenko, K.; Michał Łach; Maria Hebdowska-Krupa; Janusz Mikuła. Impact of Flax Fiber Reinforcement on Mechanical Properties of Solid and Foamed Geopolymer Concrete. Adv. technol. innov. 2021, 6, 11-20.

Speaker: Beata Figiela (Politechnika Krakowska im. Tadeusza Kościuszki)

14:15 Circular Utilization of Recycled Concrete Fines for Sustainable and Low-Carbon Mortars

The construction sector is under increasing pressure to reduce greenhouse gas emissions, decrease its reliance on virgin raw materials, and implement circular economy principles. The valorization of recycled concrete fines (RCF) as a supplementary cementitious material offers a promising route for reducing clinker consumption and natural raw materials, lowering the carbon footprint of cement-based products, and improving resource efficiency in the construction industry. This study investigates the mechanical activation of RCF and its utilization as a partial replacement of Portland cement (PC) in cement mortars. RCF derived from waste concrete was mechanically activated using different milling protocols employing both a conventional ball mill and a high-energy planetary mill. Various material-to-ball ratios, milling speeds, and activation times were evaluated to identify the most effective activation pathway. The optimal activation conditions were achieved using a ball mill with a material-to-ball ratio of 10.4, milling speed of 70 rpm, and activation time of 20 min. Structural and geometrical activity were evaluated through chemical and mineralogical characterization, particle size distribution, and surface area analysis, while the reactivity of the activated material was assessed using the activity index. The mechanically activated RCF was incorporated into cement mortars as a replacement for PC at levels from 5 to 15 wt.%. The fresh and hardened properties of the mortars were evaluated, and the microstructure of the hardened mortars was also examined. All mortars containing activated RCF exhibited longer setting times and lower mechanical properties in comparison to the reference mortars; however, all mixtures satisfied the performance requirements for mortar applications.

Speaker: Irina Stefanovska

14:30 Photocatalytic degradation of 2,5-diphenyl-1,3-oxazole and 2-(4-biphenyl)-5-phenyl-1,3,4-oxadiazole using nanoflowers

Rare earth elements, ZnO nanoflowers, scintillators.

Speaker: Mr Trajce Trajkov (Department of General and Inorganic Chemistry, Faculty of Chemistry and Pharmacy, University of Sofia)

14:45 Raw Wool Scouring – Different Detergents and their scouring results

The revival of regional wool processing requires sustainable and decentralised methods for scouring raw wool. In this context, the Department of Textile Technology of Chemnitz University of Technology is developing a compact wool scouring machine for small and medium-sized manufacturers together with environmentally friendly washing processes. The aim is to provide a resource-efficient alternative to the big, centralised wool scouring facilities.
The research focuses on a modular wool scouring system with mechanical pre-cleaning, washing and rinsing stages, and a centrifuge unit to reduce wastewater carryover. A key challenge is the machine design and the scouring parameters in combination with scouring process.
Initial laboratory trials with Saxon raw Merino wool investigated different detergents, including industrial surfactant-based detergents, traditional potash cleaning, and a plant-based solution made from horse chestnuts. Cleaning performance was evaluated using CIE whiteness and yellowness measurements.
The results showed that all washing systems improved the optical properties of the wool. The highest whiteness values were achieved with surfactant-based detergents, especially “Power Scour.” The horse chestnut solution also demonstrated good cleaning performance and strong potential as a sustainable option for decentralized wool washing, while potash cleaning was less effective and partly increased fibre felting.
Overall, both surfactant-based and plant-based scouring methods are promising approaches for sustainable regional wool processing. Future work will optimise process parameters and evaluate residual grease content and wastewater sustainability.

Speaker: Holger Cebulla (Chemnitz University of Technology)

15:00 Coffee Break

15:30 Electrospun PLA/Tuff Composite Membranes: Fabrication, Structural Characterization, and Potential for Metal Adsorption

Electrospinning enables the fabrication of micro- and nanofibrous materials with high surface area and porosity, making them attractive for water treatment and environmental remediation applications. In this study, electrospun polylactic acid (PLA) membranes containing 0, 2, 5, and 10 wt% natural opalized tuff were successfully fabricated and evaluated as eco-friendly adsorbents for heavy metals removal. The incorporation of tuff provided active mineral sites, while the PLA matrix ensured structural stability and biodegradability. Scanning electron microscopy (SEM) revealed a uniform fibrous morphology with well-developed porosity (Figure 1, left images). X-ray diffraction and Fourier-transform infrared spectroscopy confirmed the successful incorporation of tuff without altering the chemical structure of PLA. Energy Dispersive X-Ray (EDX) spectroscopy analysis demonstrated the effective adsorption of Ni2+ (Figure 1, right) and Pb2+ ions from aqueous solutions, indicating the important role of the silicate-rich mineral phase in the metal uptake.

Figure 1. SEM–EDX characterization of electrospun PLA-TUFF-0 and PLA-TUFF-10 membranes after 6 h exposure to Ni2+ solution.

The combination of a renewable polymer and a naturally occurring mineral filler resulted in porous composite membranes with promising adsorption performance.

Keywords: Electrospinning; Polylactic acid (PLA); Opalized tuff; Heavy metals adsorption, Biodegradable composites.

Speaker: Aleksandra Ivanoska-Dacikj (Macedonian Academy of Sciences and Arts)

15:45 GOLD-DECORATED REDUCED GRAPHENE OXIDE NANOHYBRIDS FOR HIGH-PERFORMANCE ELECTROCATALYTIC SENSING OF DOXORUBICIN

Screen-printed carbon electrodes (SPCEs) are crucial for point-of-care diagnostics but often require surface modification to meet clinical sensitivity demands. This study presents the development of high-performance electrochemical sensors utilizing reduced graphene oxide (rGO) decorated with gold nanoparticles (AuNPs) at varying concentrations (0.5, 2, and 4 wt.%). Structural and thermal analysis (XRPD, FTIR, Raman, SEM/EDS, TGA) confirmed successful nanohybrid formation, with Raman spectroscopy revealing a G-band redshift indicative of strong electronic interaction via n-type doping. The 2 wt.% AuNP/rGO hybrid demonstrated the highest graphitic ordering and thermal stability and was selected to modify SPCEs for the electrocatalytic detection of the anticancer drug doxorubicin (DOX).
Voltammetric analysis of the engineered sensor showed a highly favorable quasi-reversible redox process, resulting in a 3.3-fold increase in anodic peak current density (18.912 A cm-2) compared to bare SPCEs. Electrokinetic investigations confirmed accelerated electron transfer kinetics, yielding a reduced Tafel slope (140 mV dec-1) and an elevated heterogeneous rate constant (k0 = 2.57  10-5 cm s-1). Ultimately, the sensor delivered a 1.45-fold increase in sensitivity (0.221 A / mol L-1) and a 20.9% improvement in the limit of detection (13.193 mol L-1) in the low concentration range (0.5 - 10.5 mol L-1). These results highlight the potential of AuNP/rGO frameworks for next-generation, high-sensitivity screen-printed sensors.

Keywords: screen-printed electrodes, electrochemical sensor, doxorubicin, reduced graphene oxide, gold nanoparticles.

Speaker: Ms Iva Dimitrievska (Faculty of Technology and Metallurgy - Skopje)

16:00 DETECTION OF 2,4-DIMETHYLBENZOIC ACID USING ZWITTERIONIC LIGNIN-BASED POLYMER COMPOSITES

To develop sustainable functional polymer-lignin composites, the lignin was modified with zwitterionic (L)/3-[(2-methacryloyloxy)ethyl]dimethylammonio propane sulfonate (DMAPS) oligomers grafted in situ from its surface in different mass ratios (1:1, 1:2, and 1:3) via an UV-induced thiol–ene reaction. Successful surface functionalization was confirmed by FTIR, XPS, and colloidal analysis. The L/DMAPS hybrids were subsequently employed as stabilizer in the Pickering miniemulsion polymerization of methyl methacrylate/butyl methacrylate to prepare functional polymer composites. Compared with unmodified lignin, the L/DMAPS hybrids exhibited improved dispersion within the polymer matrix, enhanced filler–matrix interactions, and promoted the formation of a more homogeneous microstructure. The composites were then functionalized with 2,4-dimethylbenzoic acid (DMBA) to be make its surface sensitive to similar compounds. The influence of L/DMAPS on adsorption behaviour and sensing performance toward DMBA was evaluated. Quartz crystal microbalance (QCM) measurements were performed to monitor the adsorption and desorption of DMBA from aqueous solutions (0.01 and 0.02 mg/mL), revealing that the 1:1 L/DMAPS/polymer composite exhibited the highest adsorption capacity while maintaining reversible binding characteristics. In comparison with the L/polymer composite, the incorporation of L/DMAPS facilitated the formation of selective recognition sites through the synergistic contribution of ionic interactions, π–π interactions, and steric complementarity. These results demonstrate that the optimized L/DMAPS hybrid composite is a promising sustainable material for the selective recognition and detection of organic pollutants.

Keywords: lignin/dmaps hybrids, pickering miniemulsion polymerization, selective adsorption

Speaker: Marija Prosheva (Faculty of Technology and Metallurgy)

16:45 → 18:45 Parrallel E-Poster Presentations (1C)

16:45 VALORISATION POTENTIAL OF PROKUPAC GRAPE POMACE: MINERAL PROFILE AND LC–MS-BASED CHARACTERISATION OF BIOACTIVE COMPOUNDS IN AQUEOUS EXTRACT

Grape pomace represents an important winery by-product with significant potential for valorization as a source of minerals and bioactive compounds. In this study, an aqueous extract of grape pomace obtained from the autochthonous Serbian cultivar Prokupac was analyzed in order to evaluate its mineral profile determinate by ICP-OES method and phytochemical composition determined by LC–MS analysis. The plant material was prepared by drying the grape pomace and seeds in a drying oven at 40°C, followed by grinding in a mill. Subsequently, an aqueous extract of the plant material (1:20, w/v) was obtained at 50°C for 30 minutes using a magnetic stirrer. The extract was then centrifuged and filtered through 0.45 μm filters. The mineral profile, expressed in ppm, showed that phosphorus, calcium and magnesium were the dominant elements, with concentrations of 96.9, 84.2 and 32.66 ppm, respectively. Lower concentrations of silicon, sodium, iron, zinc, copper and manganese were also detected, indicating the presence of nutritionally relevant macro- and microelements. Cadmium, arsenic and lead were not detected, which is favorable from the perspective of potential application in food, nutraceutical or cosmetic products. LC–MS analysis revealed the presence of several bioactive compounds, including tartaric acid, taxifolin, gallic acid hexoside, aromadendrin isomer, dihydrophaseic acid hexoside, p-coumaric acid hexoside, quercetin hexoside, syringetin hexoside, isorhamnetin hexoside, trihydroxy-octadecenoic acid and dihydroxy-octadecadienoic acid. The detected compounds belong mainly to organic acids, phenolic acid derivatives, flavonoids and oxidized fatty acid derivatives, which may contribute to the antioxidant and functional potential of the extract.
The obtained results indicate that aqueous extraction can be an effective and environmentally acceptable approach for recovering mineral constituents and polar bioactive compounds from Prokupac grape pomace. This supports the potential use of this by-product as a sustainable raw material for the development of value-added food, nutraceutical or cosmetic formulations within the concept of circular bioeconomy.

Keywords: Prokupac; grape pomace; aqueous extract; minerals; ICP-OES, LC–MS.

Speakers: Mrs Nadja Ilic (University of Nis, Faculty of Technology, Bulevar oslobodjenja 124, 16000 Leskovac, Serbia), Jana Cvetkovic (University of Nis, Faculty of Technology)

16:50 INFLUENCE OF DNA EXTRACTION METHODS ON DNA QUALITY, POLYPHENOL CONTENT AND PCR-HRM PERFORMANCE IN STACHYS SPECIES

Species of the genus Stachys (Lamiaceae) are widely distributed medicinal and aromatic plants characterized by considerable morphological diversity and rich phytochemical composition. Molecular identification of Stachys species requires high-quality DNA. However, the presence of secondary metabolites, particularly polyphenols, may interfere with DNA isolation and downstream molecular analyses. This study compared three DNA extraction approaches: a cetyltrimethylammonium bromide (CTAB)-based protocol, the Edwards method based on sodium dodecyl sulfate (SDS), and a commercial QIAGEN DNA extraction kit.
Genomic DNA was isolated from dry Stachys samples and evaluated in terms of DNA yield, purity, polyphenol content, and suitability for quantitative PCR (qPCR) and PCR-high resolution melting (PCR-HRM) analysis. Species-specific primers targeting the ITS1 region were used for amplification and HRM analysis.
The Edwards protocol yielded the highest DNA concentration (248.3 ± 27 ng/µL), followed by the CTAB method (108.5 ± 16 ng/µL), while the commercial QIAGEN kit produced substantially lower DNA concentrations (52.5 ± 7 ng/µL). DNA purity (A260/A280) was relatively low for both the Edwards and CTAB methods (1.1) and slightly higher for the commercial kit (1.3). The concentration of co-extracted polyphenols was highest in Edwards extracts (22.6 ± 2.3 mg GAE/L), followed by CTAB extracts (7.1 ± 0.6 mg GAE/L), and lowest in DNA isolated using the commercial QIAGEN kit (4.8 ± 0.2 mg GAE/L).
Despite providing the highest DNA yield, the Edwards extracts exhibited pronounced qPCR inhibition, whereas DNA isolated using the CTAB protocol and the commercial kit showed efficient amplification. Additional purification of Edwards extracts with chloroform/isoamyl alcohol reduced polyphenol content (9.4 ± 0.7 mg GAE/L) and markedly improved qPCR performance, suggesting that co-extracted inhibitors, potentially including residual SDS, affected polymerase activity. PCR-HRM analysis produced comparable melting profiles among successfully amplified samples.
These findings demonstrate that DNA yield alone is not a reliable indicator of DNA suitability for molecular applications. Although the Edwards method enables rapid and efficient DNA recovery, additional purification may be required prior to PCR-based analyses of Stachys species.

Speaker: Blagica Janeva (Institute of Chemistry, Faculty of Natural Sciences & Mathematics, Ss. Cyril and Methodius University in Skopje N. Macedonia)

16:55 DETERMINATION OF TOTAL PHENOLIC CONTENT IN PELARGONIUM GRAVEOLENS L. LEAF EXTRACTS OBTAINED UNDER DIFFERENT EXTRACTION CONDITIONS USING THE FOLIN–CIOCALTEU ASSAY

Pelargonium graveolens L. is a medicinal and aromatic plant known to possess phenolic compounds with significant antioxidant potential. The extraction efficiency of these bioactive compounds depends on several experimental parameters such as the type of extraction, the solvent used for extraction, the characteristics of the plant material and the solvent-solid ratio.1,2 The aim of this study was a preliminary assessment of the influence of different extraction conditions on the total phenolic content (TPC) of extracts from Pelargonium graveolens L. leaves.
Fresh and dried leaves were extracted using two polar solvents, absolute methanol and ethanol. Three extraction techniques were investigated: maceration, ultrasound-assisted extraction and Soxhlet extraction. The influence of different solid-solvent ratios was analyzed to determine their effect on the extraction efficiency of phenolic compounds. TPC was determined spectrophotometrically using the Folin-Ciocalteu method and expressed as gallic acid equivalents (GAE) based on a calibration curve prepared with gallic acid as a reference standard.2
From the previous studies, it is evident that Soxhlet extraction method (using ethanol as a solvent) represents an efficient system to recover a high content of phenolic compounds.3 The largest amount of TPC (4.40±0.06 mgGAE/g dw) was obtained with the Soxhlet extraction using the ethanol as a polar solvent. These results may be attributed to prolonged exposure of the Pelargonium graveolens L. leaves to heated solvent and repeated solvent cycling, which can enhance the release of phenolic compounds.
The information obtained will help in optimizing the extraction of phenolic constituents from Pelargonium graveolens L. and will help in selecting extraction conditions to obtain extracts with increased phenolic content and antioxidant potential.

Speaker: Maja Sencheva Petrevska (Institute of Organic Technology, Faculty of Technology and Metallurgy, Ss. Cyril and Methodius University in Skopje, Skopje, North Macedonia)

Determination of Total Phenolic Conte.pptx

17:00 SELECTIVE MANGANESE ACCUMULATION BY SACCHAROMYCES CEREVISIAE UNDER OLEANDRIN-INDUCED STRESS

Saccharomyces cerevisiae is a valuable eukaryotic model for elucidating mechanisms of metal transport, accumulation, and homeostasis. In this study, we investigated the cellular response of yeast cells to oleandrin exposure, with particular emphasis on their capacity to accumulate heavy metals. Multi-elemental analysis revealed a selective and significant increase in intracellular Mn²⁺ levels upon oleandrin treatment, while the concentration of other metals (Co²⁺, Cu²⁺, Fe³⁺, Zn²⁺) remained largely unaffected. The enhanced accumulation of Mn²⁺ was shown to be dependent on the plasma membrane transporter Smf1, a member of the NRAMP family with high affinity for divalent metal ions2. The experiments demonstrated that Mn²⁺ uptake by yeast cells is rapid and dose-dependent, occurring within minutes after oleandrin exposure. Importantly, smf1Δ mutants failed to accumulate Mn²⁺, confirming the essential role of this transporter in metal uptake. Moreover, other mutants with defective manganese homeostasis (e. g., pmr1Δ, ahp1Δ) exhibited increased Mn²⁺ accumulation and aldo increased sensitivity to oleandrin, indicating that intracellular metal overload directly contributes to oleandrin cytotoxicity. Conversely, depletion of extracellular Mn²⁺ alleviated the toxic effects of oleandrin, further supporting the link between metal accumulation and oleandrin stress.
These findings demonstrate the yeast capacity to selectively accumulate metal ions under chemical stress and emphasise the key role of membrane transport systems in metal homeostasis, also highlighting the role of yeast as a model for studying biologically-mediated metal uptake, with applications in bioremediation, bioaccumulation, and toxicity assessment.

Speaker: Lavinia Ruta (University of Bucharest)

17:05 POLYPHENOLIC ANTIOXIDANTS MODULATE CELLULAR METAL ACCUMULATION BY SACCHAROMYCES CEREVISIAE

The interplay between polyphenolic antioxidants and metal homeostasis is a complex and increasingly relevant topic with significant implications for biotechnology and environmental applications. While polyphenols are widely recognised for their antioxidant and metal-chelating properties, their role in modulating intracellular metal accumulation remains insufficiently explored.
In this study, we used Saccharomyces cerevisiae mutants defective in metal transport to investigate how polyphenolic antioxidants influence the cellular accumulation of essential metals. We show that flavonoids such as morin and quercetin1 modulate Mn2+ and Zn2+ homeostasis, augmenting cell tolerance and, in certain cases, intracellular metal retention. These findings indicate that polyphenols not only reduce metal toxicity via chelation but also act as buffering agents that regulate bioavailable metal ions, enabling more controlled and physiologically-compatible accumulation without immediate toxicity. Moreover, metal supplementation (especially Zn2+) demonstrated that polyphenols can shift the accumulation dynamics from beneficial to toxic, highlighting their potential to modulate metal uptake through antioxidant–metal combinations.
Overall, our results support the idea that polyphenols can facilitate controlled cellular bioaccumulation of metals, with promising applications in bioremediation, metal recovery, and microbial cell factories, while requiring careful optimisation to avoid toxicity.

Speaker: Lavinia Ruta (University of Bucharest)

17:10 ANTIPLASMODIAL IN VITRO ACTIVITY AND MAMMALIAN CELL CYTOTOXICITY OF PHYTOCANNABINOIDS: ROLE OF REDOX POTENTIAL OF PHENOXY RADICAL/PHENOL COUPLE

The phenolic phytocannabinoids frequently exhibit a prooxidant activity, however, its role in their toxic/therapeutic action remains unclear. Typically, the prooxidant character of mammalian cell cytotoxicity of hydroxybenzenes is demonstrated by a negative dependence of the cytotoxicity on the redox potential of phenoxyl radical/phenol couple (E(Ph-O•/Ph-OH) or E27 at pH 7.0). Here using quantum mechanical calculations and cyclic voltammetry, the previously unknown E27 values of 10 phytocannabinoids containing resorcinol, 1-hydroxychromene or 1-hydroxychromane moieties were estimated to be 0.72 V- 0.82 V. Using the above E27 values, it was found that the cytotoxicity of phytocannabinoids in MH22a cells follows the same two-parameter regression as that of model hydroxybenzenes, i.e., a negative dependence on E27 and a positive dependence on their octanol/water partition coefficient at pH 7.0 (log.D). The protective effects of antioxidants and the potentiating effect of carmustine evidenced the predominant prooxidant character of their cytotoxicity. In contrast, the in vitro activity of phytocannabinoids against Plasmodium falciparum FcB1 strain was much greater than that of model hydroxybenzenes. Unlike their lipophilicity-independent activity, the antiplasmodial activity of phytocannabinoids increased with their log D. This enabled to suggest that the mammalian cell cytotoxicity of phytocannabinoids may be largely determined by their induced oxidative stress, but their antiplasmodial activity may be determined by other factors.
This study was partly supported by the COST Action CA21111. We thank Alberta Melenė and Renaldas Rimkus (Sanobiotec UAB, Vilnius) for their generous gift of phytocannabinoids.

Speaker: Prof. Narimantas Čėnas

17:15 PCR-HRM Discrimination of Gluten-Containing and Gluten-Free Cereals

The production and consumption of gluten-free food products have significantly increased due to the global rise in celiac disease and non-celiac gluten sensitivity. Ensuring the safety of these products remains a critical challenge, as accidental cross-contamination can occur during manufacturing, storage, or transport.
While conventional detection relies heavily on immunochemical methods like ELISA, these techniques face limitations when analyzing highly processed food matrices. Molecular DNA-based methods, particularly PCR combined with High-Resolution Melting (PCR-HRM), offer an alternative approach for the detection and discrimination of target cereal species. The aim of this study was to develop and evaluate specific PCR-HRM primers targeting the internal transcribed spacer (ITS) region for the discrimination of gluten-containing cereals from gluten-free cereals. Three primer sets (P1, P2, P3) were designed and experimentally evaluated for their specificity toward gluten-containing cereals, including wheat, barley, and rye, and their ability to discriminate them from gluten-free cereals, including oat, rice, and maize.
The first primer pair (P1) demonstrated insufficient specificity, as amplification was also observed in non-target cereal samples, limiting its ability to reliably discriminate gluten-containing from gluten-free cereals. The second primer pair (P2) improved performance but still exhibited non-specific amplification in oat samples. In contrast, the third primer set (P3) demonstrated high specificity, with clear discrimination between gluten-containing and gluten-free cereal samples. Primer performance was further evaluated by comparing amplification cycle threshold (Ct) values and the shape and characteristics of the amplification and melting curves. The selected primer set produced distinct PCR-HRM profiles: Tm in the range of 87.8 – 89.1 for wheat, barley and rye, Tm in the range of 77.9 – 81.6 for oat, rice and maize.
These results demonstrate that careful primer design and selection within the ITS region can provide a specific PCR-HRM system for the differentiation of gluten-containing and gluten-free cereals. Further optimization and validation using a broader range of reference materials and processed food matrices will be performed to determine the analytical sensitivity, detection limit, and applicability of the developed method.

Keywords: Gluten-containing cereals, PCR-HRM, ITS region, Primer specificity, Food safety

Speaker: Mihaela Nedelkovska

17:20 Synthesis and cholinesterase inhibitory evaluation of novel aryl derivatives of 2-(1H-imidazol-1-yl)acetic acid

Nitrogen-containing heterocyclic compounds based on the imidazole scaffold are frequently utilized in crop protection and medicinal chemistry due to their exceptional capacity to interact with diverse biological targets.1 In the field of agrochemicals, compounds disrupting the cholinergic nervous system through the inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) serve as vital tools for pest management and toxicological assessment. Therefore, exploring both enzymes is crucial for determining the efficacy, selectivity, and environmental safety of potential new screening candidates.2 In this study, a new series of arylamide derivatives of 2-(1H-imidazol-1-yl)acetic acid was synthesized using a modified Steglich amidation procedure under mild reaction conditions. The synthetic approach involved the use of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC × HCl) as the coupling reagent and 4-dimethylaminopyridine (DMAP) as the catalyst. Structural variation was achieved through the incorporation of differently substituted aromatic amines bearing electron-donating and electron-withdrawing groups, with the aim of exploring preliminary structure–activity relationships. The obtained compounds were characterized by melting point determination, ¹H and ¹³C NMR spectroscopy, and mass spectrometry. In addition, the synthesized derivatives were evaluated for their inhibitory activity against AChE and BuChE to assess their potential as cholinesterase inhibitors.

Keywords: 2-(1H-imidazol-1-yl)acetic acid, Steglich amidation, acetylcholinesterase, butyrylcholinesterase, cholinesterase inhibition

References:
1. Yadav, G; Jain, R. An insight into Synthetic, Structural and Medicinal perspective of imidazole analogs: A review European Journal of Medicinal Chemistry 2025, 290, 117524. https://doi.org/10.1016/j.ejmech.2025.117524

1. Karnaš, M; Rastija, V; Šubarić, D; Molnar, M. Green Synthesis and Acetylcholinesterase Inhibition of Coumarin-1,2,4-Triazole Hybrids. Curr. Org. Chem. 2023, 27, 883–892. https://doi.org/10.2174/1385272827666230817145725

Speaker: Martina Šrajer Gajdošik (Josip Juraj Strossmayer University of Osijek - Department of Chemistry)

17:25 Novel alkyl imidazole-4-carboxylic acid derivatives: Synthesis and evaluation of cholinesterase inhibiton

Imidazole derivatives are important heterocyclic pharmacophores in medicinal chemistry, well known for their broad spectrum of biological activities and therapeutic potential.1 In agricultural applications they target cholinesterases (acetylcholinesterase, AChE and butyrylcholinesterase, BuChE), which are important for the normal function of the nervous system in humans, other vertebrates and insects. Consequently, dual evaluation AChE and BuChE inhibition characterizes the potency, selectivity, and toxicological safety of newly synthesized imidazoles as agrochemicals.2
In this work, a series of novel alkylamide derivatives of 1H-imidazole-4-carboxylic acid were synthesized using a modified Steglich EDC × HCl/DMAP amidation method under mild reaction conditions. Structural modifications included the incorporation of selected aliphatic amines in order to investigate structure–activity relationships. All compounds were characterized by melting point determination, 1H and 13C NMR spectroscopy, and mass spectrometry. To achieve a comprehensive understanding of their cholinesterase inhibition profiles, the synthesized derivatives were screened for dual inhibitory activity against AChE and BuChE.

Keywords: acetylcholinesterase, butyrylcholinesterase, imidazole, 1H-imidazole-4-carboxylic acid
References:
1. Bendi, A; Vashisth, C; Devi, P; Bhathiwal, AS; Pundeer, R; Mittal, C; Raghav, N; Afshari, M. From Lab to Life: The Journey of imidazoles Through Advanced Synthesis and Vital Biological Applications (Comprehensive Review). ChemistrySelect. 2025, 10, e202500631. https://doi.org/10.1002/slct.202500631

1. Karnaš, M; Rastija, V; Šubarić, D; Molnar, M. Green Synthesis and Acetylcholinesterase Inhibition of Coumarin-1,2,4-Triazole Hybrids. Curr. Org. Chem. 2023, 27, 883–892. https://doi.org/10.2174/1385272827666230817145725

Speaker: Marija Paurević (Josip Juraj Strossmayer University of Osijek - Department of Chemistry)

17:30 Design of novel aryl imidazole-4-carboxylic acid derivatives as potential cholinesterase inhibitors

Imidazole derivatives are well known for their broad spectrum of biological activities and significant applications in medicinal and agrochemical research, including anticancer, antifungal, antibacterial, anti-inflammatory, and neuroprotective effects.1 In addition to their medicinal importance, acetylcholinesterase (AChE) inhibitors are widely used as active ingredients in insecticidal plant protection products, while butyrylcholinesterase (BuChE) is also known to be inhibited by organophosphate and carbamate pesticides and is frequently used as a biomarker of pesticide exposure. Consequently, the evaluation of both AChE and BuChE inhibition provides valuable insight into the potency, selectivity, and potential safety of newly synthesized compounds in agrochemical research.2 In this work, a series of novel arylamide derivatives of 1H-imidazole-4-carboxylic acid was synthesized using a modified Steglich amidation method with EDC × HCl and DMAP under mild reaction conditions. Structural modifications included the incorporation of aniline and meta- or para-substituted aniline moieties containing electron-donating or electron-withdrawing groups in order to investigate structure–activity relationships. All compounds were characterized by melting point determination, 1H and 13C NMR spectroscopy, and mass spectrometry. The synthesized derivatives evaluated for their inhibitory activity against both AChE and BuChE, in order to obtain a more comprehensive insight into their cholinesterase inhibition profile.

Keywords: acetylcholinesterase, butyrylcholinesterase, imidazole, 1H-imidazole-4-carboxylic acid
References:
1. Al-Ghamdi, HA; Almughem, FA; Alshabibi, MA; Bakr, AA; Alshehri, AA; Aodah, AH; Al Zahrani, NA; Tawfik, EA; Damiati, LA. Synthesis and Biological Evaluation of Novel Imidazole Derivatives as Antimicrobial Agents. Biomolecules. 2024, 14, 1198. https://doi.org/10.3390/BIOM14091198/S1

1. Karnaš, M; Rastija, V; Šubarić, D; Molnar, M. Green Synthesis and Acetylcholinesterase Inhibition of Coumarin-1,2,4-Triazole Hybrids. Curr. Org. Chem. 2023, 27, 883–892. https://doi.org/10.2174/1385272827666230817145725

Speaker: Andrea Dandić (University of Osijek, Department of chemistry)

17:40 Short discussion

17:50 SPECTROPHOTOMETRIC KINETIC STUDY OF N-ACETYLCYSTEINE ADDITION TO 2-FLUOROBENZYLIDENE CURCUMINE ANALOGS IN DIFFERENT MEDIA

Monocarbonyl analogs of curcumin (MACs) containing α,β-unsaturated carbonyl systems are electrophilic compounds capable of interacting with thiol-containing nucleophiles via thia-Michael addition.1,2 Their reactivity toward biologically relevant thiols, such as N-acetylcysteine, is important for understanding their chemical behavior and potential biological activity. In this study, we investigated the spectrophotometric kinetic behavior of two 2-fluorobenzylidene monocarbonyl analogs of curcumin, EF24 [(3E,5E)-3,5-bis(2-fluorobenzylidene)-4-piperidone] and 2FCXNON [(2E,6E)-3,6-bis(2-fluorobenzylidene) cyclohexanone], in the presence of N-acetylcysteine.
The reactions were followed by UV/VIS spectroscopy using N-acetylcysteine in excess to ensure complete reaction based on literature data.1,2 Both compounds were examined in DMSO and in 100 mM aqueous phosphate buffer/acetonitrile, 80:20 v/v (pH 7.4). Reactions were monitored for 6 h in DMSO and for approximately 30 min in the buffered medium, where faster spectral changes were observed.
EF24 showed time-dependent spectral changes in DMSO and a faster response in phosphate buffer/acetonitrile, indicating higher reactivity toward N-acetylcysteine under buffered conditions. In contrast, 2FCXNON showed no significant spectral changes in either medium under the applied experimental conditions. The reactivity of EF24 and 2FCXNON toward N-acetylcysteine was evaluated, providing preliminary kinetic data. The developed UV/VIS method is simple, reproducible, and suitable for comparative assessment of the thiol-reactivity of other MACs.

Keywords: monocarbonyl analogs of curcumin, fluorinated MACs, N-acetylcysteine, thia-Michael addition, UV/VIS kinetics, phosphate buffer.

References:
1. Amslinger, S.; Al-Rifai, N.; Winter, K.; Wörmann, K.; Scholz, R.; Baumeister, P.; Wild, M. Reactivity assessment of chalcones by a kinetic thiol assay. Org. Biomol. Chem. 2013, 11, 549–554. https://doi.org/10.1039/C2OB27163J.
2. Clariano, M.; Marques, V.; Vaz, J.; Awam, S.; Afonso, M. B.; Perry, M. J.; Rodrigues, C. M. P. Monocarbonyl analogs of curcumin with potential to treat colorectal cancer. Chem. Biodivers. 2023, 20, e202300222. https://doi.org/10.1002/cbdv.202300222.;

Speaker: Mrs Milena Spasovska Kolevska (Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, Skopje)

17:55 ASSESSMENT OF THIA-MICHAEL REACTION OF MONOCARBONYL ANALOGS OF CURCUMIN AND N-ACETYLCYSTEINE

Monocarbonyl analogs of curcumin have attracted attention due to their diverse biological activity. They contain a cross-conjugated α,β-unsaturated enone system. The cyclic derivatives possess two exocyclic C=C bonds, conjugated with the central carbonyl group, and they are well-suited to act as Michael acceptors for biologically relevant thiols. One of the key lead compounds is EF24, or (3E,5E)-3,5-bis(2-fluorobenzylidene)piperidin-4-one, with a cross-conjugated α,β-unsaturated ketone system. In this work computational methods were used to investigate the electronic characteristics of EF24 and other related MACs and their possible Michael-type reaction with N-acetylcysteine (NAC), selected as a representative thiol-containing biomolecule.
Calculations were done in HyperChem using the PM3 method, analyzing optimized EF24 and related MACs, neutral NAC (NAC–SH), its thiolate form (NAC–S⁻), and the MACs–NAC adduct. HOMO/LUMO energies, HOMO-LUMO gap and dipole moment were used as semiempirical descriptors to assess MACs electrophilicity and the nucleophilic behavior of NAC, particularly in its thiolate form.
The analysis focused on the LUMO distribution of EF24, particularly at the β-carbon atoms of the exocyclic C=C bonds, which were considered the most probable sites for nucleophilic sulfur attack. The HOMO of NAC–S⁻ was examined to confirm the localization of electron density on the sulfur atom. Compared with neutral NAC–SH, which showed weaker nucleophilic character, NAC–S⁻ was identified as the more reactive species involved in the proposed Michael-type addition. Therefore, the interaction between the HOMO of NAC–S⁻ and the LUMO of EF24 was used as the main basis for explaining the EF24–NAC interaction.

Keywords: MACs, EF24, N-acetylcysteine, Michael acceptor, HOMO-LUMO, PM3, thiol addition

References:
1. Clariano, M.; Marques, V.; Vaz, J.; Awam, S.; Afonso, M. B.; Perry, M. J.; Rodrigues, C. M. P. Monocarbonyl Analogs of Curcumin with Potential to Treat Colorectal Cancer. Chem. Biodiversity 2023, 20, e202300222. https://doi.org/10.1002/cbdv.202300222.
2. Ting, J. Y. C.; Roseli, R. B.; Krenske, E. H. How does cross-conjugation influence thiol additions to enones? A computational study of thiol trapping by the naturally occurring divinyl ketones zerumbone and α-santonin. Org. Biomol. Chem. 2020, 18, 1426–1435. https://doi.org/10.1039/C9OB02709B.

Speaker: Milena Spasovska Kolevska (Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, Skopje)

18:00 Synthesis, Comparison of Spectroscopic Properties and In Silico Analysis of Some Acyclic Derivatives of C5-Curcuminoids

Although curcumin (CUR) has significant beneficial effects and biological activity, its clinical applications are limited due to its poor bioavailability, low absorption, rapid metabolism and low chemical stability. One approach to enhance the bioavailability of CUR is through the structural modification of its molecule. C5-curcuminoids (C5-CUR) that lack a β-diketone moiety in their structure possess greater metabolic stability and bioactivity than CUR, increased stability in vitro, and improved pharmacokinetic profile in vivo. These compounds have been extensively studied and exhibit various beneficial biological properties.
In this study, six C5-CUR were synthesized and their biological activity was predicted in silico using the online platforms SwissADME and Protox-3.0. The synthesis was carried out via Claisen-Schmidt condensation reaction between various aromatic aldehydes and acetone, catalyzed by sodium hydroxide. The synthesized compounds were characterized using melting points and spectroscopic techniques. The indicative spectroscopic characteristics of these cross-conjugated derivatives is the C=O stretching band that is below 1700 cm-1. They all show UV-Vis absorption peak above 300 nm.
The drug-likeness analysis confirmed that most of the synthesized compound fulfilled the criteria of Lipinski’s Rule of Five, indicating favorable pharmacokinetic properties and potential oral bioavailability. Furthermore, the in silico toxicity assessment revealed a low predicted toxicological risk, suggesting that the synthesized C5-curcuminoid derivatives represent promising candidates for further biological evaluation.

Keywords: C5-curcuminoids, spectroscopic properties, in silico analysis.

Speaker: Mr Arjan Ganiji (Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, Arhimedova 5, 1000 Skopje, R. N. Macedonia; Faculty of Technology Science, Mother Theresa University, Mirce Acev 4, 1000 Skopje, R. N. Macedonia)

18:05 COMPUTER-AIDED DESIGN, ADMET PREDICTION, AND TOXICITY ASSESSMENT OF NOVEL SYNTHETIC FLAVANONES

This study presents a two-step in silico strategy for the rational design of flavanone derivatives with improved antioxidant activity and favorable pharmacokinetic properties.1 Experimental vitamin C equivalent antioxidant capacity (VCEAC) data for flavanones were used to develop QSAR models based on ChemSketch descriptors. The models showed excellent statistical performance, with R² values exceeding 0.99 and low prediction errors, confirming their suitability for antioxidant activity prediction.2 The results indicate that antioxidant activity is influenced by electronic, structural, and physicochemical properties, including polarity, molecular size, and hydroxyl substitution.3
A ChemSketch-based QSAR model was further evaluated of in silico design of six new flavanone derivatives. The designed compounds were assessed based on predicted antioxidant activity, Lipinski drug-likeness parameters, and GUSAR toxicity profiles. Increasing hydroxyl substitution significantly enhanced predicted antioxidant capacity, showing a strong linear relationship with VCEAC (R² = 0.9995).
The most promising derivative was identified based on the combined evaluation of antioxidant potency, predicted safety, and drug-like properties. Overall, the findings show the potential of integrated QSAR-guided in silico design for developing new flavanone-based antioxidant candidates.

Speaker: Maja Sencheva Petrevska (Institute of Organic Technology, Faculty of Technology and Metallurgy, Ss. Cyril and Methodius University in Skopje, Skopje, North Macedonia)

COMPUTER-AİDED DESİGN.pptx

18:10 ENANTIOSELECTIVE OXIDATION AND CHIRAL CHROMATOGRAPHIC PROFILING OF SULFOXIDES FOR CHIRAL BIOANALYSIS

Chiral sulfoxides are valuable motifs in organic synthesis, medicinal chemistry, and pharmaceutical research. The present study addresses a central methodological challenge in biochirality research: how to control, monitor, and analytically resolve stereochemical outcomes in small chiral molecules. A series of aryl sulfides bearing electron-donating and electron-withdrawing substituents at different aromatic positions was subjected to enantioselective oxidation in order to evaluate the influence of substrate electronics and substitution pattern on reactivity and stereochemical induction.1
Preliminary experiments indicate that suppression of non-selective background oxidation and optimization of the Ti:DET ratio are important for maintaining enantiomeric enrichment. Use of opposite diethyl tartrate enantiomers, R,R-DET and S,S-DET, in separate catalyst-complex formation experiments led to a reversal of enantioselectivity, with the opposite sulfoxide enantiomer becoming predominant in each case. The products are profiled by chiral HPLC on polysaccharide-based chiral stationary phases to determine enantiomeric excess and evaluate structure-selector relationships. Presented as an ongoing methodological project rather than a fully completed study, this work invites discussion on improving catalyst assembly, asymmetric oxidation conditions, and chromatographic strategies for reliable profiling of small chiral molecules relevant to biochirality research.

Keywords: HPLC, enantiomers, sulfoxides.

References: Konjaria, M.-L.; Kakava, R.; Volonterio, A.; Chankvetadze, B.; Scriba, G. K. E. Enantioseparation of chiral (benzylsulfinyl)benzamide sulfoxides by capillary electrophoresis using cyclodextrins as chiral selectors. J. Chromatogr. A 2022, 1672, 463027. https://doi.org/10.1016/j.chroma.2022.463027.

Speaker: Dr Rusudan Kakava (Tbilisi State University)

18:15 Comparative Evaluation of Drying Methods in the Manufacturing of Granules for Oral Suspension

The critical quality attributes of the drug product and the efficiency of the manufacturing process for production of granules for oral suspension be affected by the the drying process. The impact of three different drying technologies single‑pot vacuum, fluid bed, and tray drying on granules produced by wet granulation was evaluated. An immediate‑release formulation containing a BCS class IV active pharmaceutical ingredient was prepared, and granules were characterized in terms of particle size distribution, loss of drying, porosity, and flowability, while the finished product was evaluated for assay and related substances.
Single‑pot and fluid bed drying improved process efficiency compared to tray drying, while vacuum drying enabled lower product temperature. Loss of drying met the specified acceptance criterion (≤ 2.0%) for all systems, with improved moisture homogeneity under dynamic conditions. Drying technology affected particle size distribution, whereas porosity and flowability remained comparable.1
Despite differences in granule characteristics, final product quality attributes were consistent across all drying technologies. XRPD and FT‑IR analyses indicated that the crystalline form of the active substance remained unchanged, suggesting the absence of polymorphic transformation. Overall, drying technology influences granule properties and process efficiency without significantly affecting critical quality attributes. 1,2

Keywords: drying technology; granules for oral suspension; particle size distribution; loss of drying; process efficiency

Speaker: Viktorija Bezhovska (Alkaloid AD Skopje, Blvd. Aleksandar Makedonski 12, 1000 Skopje, Republic of North Macedonia)

18:20 Configuration and Validation of method for determination of Sulphated Ash in LabX software

The determination of sulphated ash is a compendial analytical method, as prescribed in the European Pharmacopoeia, for the quantification of inorganic impurities in pharmaceutical and chemical substances. This study describes the configuration and validation of a sulphated ash calculation method using the LabX laboratory software system.
The method enables automated data capture and calculation based on predefined variables and formulas, supporting data integrity throughout the data life cycle while ensuring that system-generated results comply with the ALCOA+ principle. Validation was performed independently using Microsoft Excel with experimental datasets from two samples subjected to repeated ignition. The results showed excellent agreement between LabX and Excel calculations, confirming the correctness and reliability of the configured method.
The study highlights the importance of proper configuration, traceability, and independent validation in ensuring compliance with regulatory requirements and improving analytical accuracy.

Speaker: Ivana Atanasova (Quality Control Pharmaceuticals, ALKALOID AD Skopje)

Configuration and Validation of method for determination of Sulphated Ash in LabX software_e poster.pptx

18:25 Risk assessment for reducing the number of ongoing stability studies in order to improve process efficiency and reduce chemical and pharmaceutical waste

ABSTRACT
In the pharmaceutical industry, ongoing stability monitoring of commercial batches is a mandatory requirement that often generates a large volume of samples and analytical tests, many of which provide redundant data for well-established products. This paper explores a quality risk management (QRM) approach, aligned with ICH Q1A (R2) and Q9 guidelines, aimed at streamlining ongoing stability protocols.
The study defines risk-based criteria to support the reduction of the number of batches included in the ongoing stability program, as well as the implementation of reduced testing frequency for products with well-established historical stability data. This strategic optimization improves operational efficiency within the Quality Control (QC) laboratory by reducing sample throughput and shortening analytical lead times. Furthermore, it significantly contributes to sustainability efforts by minimizing the consumption of organic solvents (e.g.HPLC waste) and reducing overall pharmaceutical and chemical waste. The proposed model provides a robust framework that maintains strict GMP compliance while enhancing cost-effectiveness and reducing environmental impact.

Speaker: Elena Stankovska (Alkaloid AD Skopje)

Risk Assessment for reducing the number of ongoing stability studies_E.Stankovska.pptx

18:30 Comparative study of two medical grade HDPE Bormed HE7541PH vs Purell ACP6541A

The comparative evaluation between Bormed HE7541 PH and Purell ACP6541A as medical grade resins is important because both materials are widely used in Pharmaceutical packaging applications where mechanical performance, processability and regulatory compliance are critical. Bormed™ HE7541-PH is a bimodal high density polyethylene intended for evaluation for use in Healthcare applications and is typically used in articles produced via injection moulding. Typical applications are (caps, closures, shoulders for tubes, containers for tablets, powder or granules). 1 Supplier Technical Data sheet. Exceptional organoleptic properties and outstanding balance of stiffness, toughness and environmental stresscracking resistance make Purell ACP6541A appropriate for the production of closures for still mineral and sparkling water, CSD (soft carbonated drinks) and many other types of food and non-food caps and closures (incl. hinge caps) as well as tube shoulders and compression moulding applications. Purell ACP6541A is additionally used in injection moulding applications. 2 Supplier Technical Data sheet

The objective of this abstract is to evaluate key mechanical and processing properties of two medical-grade HDPE resins BORMED™ HE7541PH and PURELL ACP6541A. The significantly higher MFR (Melt Flow Rate) of Bormed™ HE7541PH indicates lower melt viscosity and easier processability. PURELL ACP6541A with lower MFR, suggests higher molecular weight providing improved mechanical robustness. Similar tensile modulus values indicate comparable stiffness. Differences in hardness and tensile strength reflect variations in material rigidity and flexibility. Both HDPE resins demonstrate suitability for pharmaceutical packaging applications, but significant differences in melt flow rate and mechanical properties indicate that material substitution should be carefully validated based on processing conditions, performance requirements and regulatory compliance. 3 ISO 1133-1, ISO-527, ISO 868
Keywords: HDPE, Injection moulding applications, Melt Flow Rate, Tensile properties of plastic
References: 1,2 Supplier Technical Data sheet 3 ISO 1133-1, ISO-527, ISO 868.

Speaker: Mr Nikola Pavleski (Alkaloid AD)

OBPC-P20-Comparative study of two medical grade HDPE Bormed HE7541PH vs Purell ACP6541A.pptx

16:45 → 18:45 Parrallel E-poster Presentations (1B)

16:45 NMR Profiling of European Oak Honeydew Honeys: Saccharide Diversity and Geographical Differentiation

This study investigates whether the chemical composition of European oak honeydew honeys reflects the geographical origin. Sixty samples from Bulgaria, Germany, Greece, Italy, North Macedonia, Romania, Serbia, and Spain were analyzed using semiquantitative 13C nuclear magnetic resonance (NMR) spectroscopy. The protected designation of origin (PDO) Strandzha honey was compared to honey from other regions in Bulgaria. Statistical analysis differentiated country groups through combinations of variables rather than a single marker.

A new pattern that had not previously been observed in European honey was identified: two coordinated saccharide networks showed that minor sugars fluctuate together rather than independently. Conventional honeydew-associated indicators were re-examined and it was found that melezitose is not a necessary component of oak honey. In contrast, 1-kestose was present in all samples. While extended 13C NMR profiling may support geographical characterization, independent validation is required before it can be used for authentication purposes.

Keywords: European oak honey, geographical origin, NMR metabolomics
Acknowledgement: Projects КP-06-COST/10, INFRAMAT and BIORESOURCES BG

Speaker: Svetlana Simova (Bulgarian NMR Centre, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences)

16:50 RIBOFLAVIN AND THIAMINE CONTENT IN COMMERCIAL ALMOND MILK

Long valued for its distinct taste, almond beverage has recently emerged as one of the leading plant-based milk alternatives. Vegans and people with lactose intolerance use almond milk as a healthy substitute for dairy products. Almond milk offers fewer calories than cow milk, mainly because it has less protein and fewer carbohydrates when unsweetened. Almond milk is produced by blending water with almond paste or powder. It generally contains water, almonds, salt, added vitamins and minerals, and stabilizers and preservatives. During commercial manufacturing, almond liquid undergoes high-pressure homogenization and pasteurization to enhance product stability and shelf life. However, recent studies indicate that these thermal and mechanical treatments can alter the physical properties of the beverage1.
Riboflavin (vitamin B2) and thiamine (vitamin B1) are essential water-soluble B-vitamins which are coenzymes in cellular energy metabolism, support normal growth, and maintain a healthy nervous system. The aim of this work was to determine the riboflavin and thiamine content in commercial almond milk.
Commercial almond milk with 1.1% fat and 2% of almonds was from the local market. HPLC analysis with fluorescence detection was conducted on the C18 column using the mobile phase consisting of 30.0% methanol and 70.0% 0.005M NH4Ac (pH 5.0). The sample was prepared by protein precipitation using perchloric acid. After vortexing and centrifugation, a clear supernatant was obtained. Riboflavin was analyzed directly after filtration through a membrane filter. To analyze thiamine, the supernatant was derivatized with 1% potassium ferricyanide in 15% sodium hydroxide.
The concentration of riboflavin in commercial almond milk was found to be 1.884±0.124 µg/ml (RSD 6.6%), while thiamine content was 1.20±0.13 ng/ml (RSD 10.8%). In the almond milk sample, the concentration of riboflavin was significant, while thiamine was present in very low concentrations. The findings confirm that almond milk may be a good source of riboflavin in a vegan/plant-based diet.

Speakers: Mrs Slavica Sunarić, Slavica Sunarić (Faculty of Medicine, University of Niš, serbia)

16:55 Optimization and Application of a Method for Determining the Aromatic Profile of Macedonian White Wines Using Gas Chromatography Coupled with Mass Spectrometry

Wine aroma is one of the most important characteristics of wine quality and is determined by a complex mixture of volatile compounds. In this work, volatile aromatic compounds in Macedonian white wines were investigated using gas chromatography coupled with mass spectrometry (GC-MS) and two capillary columns with different stationary-phase polarities (HP5-MS with 5 % phenyl, and DB-1701 with 14 % - cyanopropyl-phenyl. Liquid-liquid extraction with dichloromethane was selected as the most suitable sample preparation procedure and was subsequently optimized to obtain optimal extraction conditions starting from 10 mL of wine and 1 mL dichloromethane and addition of 1 g of (NH4)2SO4 for pH control and 1-octanol as an internal standard.
The developed method was tested with a standard mixture of alcohols, esters, acids and terpenes and showed good sensitivity and reproducibility, with LOD values between 0.04 and 0.29 µg/mL and LOQ values of 0.41–2.93 µg/mL. Most investigated compounds showed RSD values below 10 %, indicating good analytical precision. The two columns showed complementary chromatographic characteristics. HP-5MS provided better detection of less polar compounds, particularly terpenes and long-chain ethyl esters, while DB-1701 showed improved detection and peak shape for more polar compounds, especially for carboxylic acids.
Application of the method to different Macedonian white wine varieties revealed a complex profile of alcohols, esters, terpenes, and carboxylic acids. Hexan-1-ol,
2-phenylethanol, isoamyl acetate, and several ethyl esters were consistently detected and represented important components of the wine aroma. The results demonstrate that the combined use of HP-5MS and DB-1701 enables more reliable identification and comprehensive characterization of the different classes of volatile aromatic compounds in Macedonian white wines.

Speaker: Hristina Trisheska

17:00 COMPARISON OF DEEP EUTECTIC SOLVENTS FOR THE EXTRACTION OF POLYPHENOLIC COMPOUNDS FROM Salvia officinalis L.

Polyphenolic compounds derived from medicinal plants have attracted considerable attention due to their antioxidant, antimicrobial, and pharmacological properties. In recent years, deep eutectic solvents (DESs) have emerged as environmentally friendly alternatives to conventional organic solvents for the extraction of bioactive compounds, supporting the principles of green chemistry.
The extraction of polyphenolic compounds from Salvia officinalis L. (sage) was investigated using a series of deep eutectic solvents (DESs) as sustainable alternatives to conventional organic solvents. Nineteen choline chloride-based DES systems were prepared and evaluated, while 70% methanol was used as a reference solvent. Plant samples were subjected to ultrasound-assisted extraction, and the resulting extracts were analyzed by high-performance liquid chromatography coupled with diode-array detection and mass spectrometry (HPLC-DAD-MS).
Quantitative analysis focused on the major classes of bioactive compounds present in sage extracts, including phenolic acids, flavonoids, procyanidins, and terpenoids. The results demonstrated that 70% methanol provided the highest extraction yield of phenolic acids (26.55 mg/g) and terpenoids (1.64 mg/g). However, several DES systems exhibited superior selectivity toward specific classes of compounds. In particular, choline chloride–tartaric acid [ChT(1:2)] achieved the highest flavonoid content (81.31 mg/g), substantially exceeding that obtained with methanol (16.49 mg/g). Choline chloride–urea [ChU(1:2)] and choline chloride–acetic acid [ChA(1:2)] also showed enhanced flavonoid extraction efficiency. The extraction of procyanidins remained relatively low in all investigated systems, although ChA(1:2) and ChU(1:2) provided slightly higher yields than methanol.
The findings indicate that the composition and physicochemical properties of DESs strongly influence their extraction performance and selectivity. While methanol remains highly effective for the extraction of phenolic acids and terpenoids, DES systems based on tartaric acid and urea represent promising green alternatives for the selective extraction of flavonoids. Their low toxicity, biodegradability, and tunable properties support their potential application in sustainable extraction processes for natural bioactive compounds.

Keywords: Salvia officinalis L.; deep eutectic solvents (DESs); green extraction; polyphenolic compounds; flavonoids; HPLC-DAD-MS; sustainable solvents

Speaker: Merva Ejupi (Institute of chemistry, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University in Skopje, Macedonia)

17:05 VOLATILE COMPOUND DIVERSITY IN Salvia SPECIES REVEALED BY GC–HS–MS ANALYSIS

Plants belonging to the genus Salvia are well known for their aromatic properties, which arise from a diverse mixture of volatile compounds. These compounds, primarily monoterpenes, oxygenated monoterpenes, sesquiterpenes, and oxygenated sesquiterpenes, represent the major constituents of Salvia essential oils and contribute significantly to their characteristic aroma and biological activity. The present study aimed to characterize and compare the volatile profiles of 33 Salvia species using headspace gas chromatography–mass spectrometry (GC–HS–MS).
Volatile compounds were identified by comparison of the obtained mass spectra with the NIST spectral database. A total of 132 volatile compounds were detected, demonstrating the remarkable chemical diversity within the investigated species. Among the identified compounds, 19.7% were classified as monoterpenes, 16.7% as oxygenated monoterpenes, 36.4% as sesquiterpenes, 14.4% as oxygenated sesquiterpenes, while the remaining 12.9% belong to other compound classes, including aldehydes, ketones, alcohols and esters. Sesquiterpenes represented the dominant class in most species, although considerable interspecific variation was observed.
The highest number of volatile constituents (48 compounds) was identified in Salvia officinalis Purpuresens. Its volatile profile was characterized by the predominance of (−)-β-pinene (11.33%), Z,Z,Z-1,5,9,9-tetramethyl-1,4,7-cycloundecatriene (10.23%), α-thujone (7.53%), camphor (7.04%), cyclofenchene (5.85%), and camphene (5.53%).
Comparison of the volatile profiles revealed substantial qualitative and semi-quantitative differences among the investigated species. The observed variability reflects both species-specific characteristics and the influence of environmental factors, highlighting the importance of volatile compound profiling for understanding the chemical diversity of the genus Salvia and supporting its potential applications in pharmaceutical, cosmetic, food, and aromatic plant research.

Keywords: Salvia, sesquiterpenes, monoterpenes, essential oils, GC-HS-MS, Salvia officinalis Purpuresens

Acknowledgements: This work has been supported by Macedonian Ecological Society for the financial support of the project titled ”Integrated Strategy for Taxonomic Discrimination of Salvia Species Based on Chemical and Genetic Markers”.

Speaker: Anastasija Hadzismileva (Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University in Skopje, Skopje, North Macedonia)

17:10 OPTIMIZATION OF A NOVEL EXTRACTION METHOD FOR THE ISOLATION OF ANTHOCYANINS FROM BERRY FRUIT POMACE

The valorization of berry pomace (aronia, blueberry, blackberry, raspberry) as a secondary raw material rich in biologically active compounds has become an attractive topic in recent years.1 Circular economy principles are driving numerous studies aimed at finding ways to transform this industrial by-product into a raw material for various applications.
In this study, the extraction of anthocyanin pigments, present in high concentrations in these samples, was approached using novel solvents prepared on the principles of green chemistry. Several different solvents with the properties of deep eutectic systems (DESs) were prepared, and the most chemically stable ones were selected for the extraction experiments. For the solvent preparation, choline chloride, choline dihydrogen citrate, and sodium acetate were used as hydrogen bond acceptors (HBAs), while glycerol and polyethylene glycol were used as hydrogen bond donors (HBDs). The efficiency of the tested solvents was compared to that of methanol used in the conventional extraction method performed on the same samples.2,3 In both cases, anthocyanin quantification was carried out using UV/VIS spectrometry.
Obtained results showed significant improvement of extraction efficiency, compared to the control sample: the highest extraction efficiency was achieved for blackberry samples using the choline chloride/polyethylene glycol solvent system.
The results of this study confirm that the proposed solvent systems are promising extraction tools that can significantly contribute to reducing the food industry's environmental footprint and fostering sustainable resource management.

Speakers: Jasmin Suljagić (University of Tuzla), Mersiha Suljkanovic (University of Tuzla)

17:15 SUSTAINABLE VALORIZATION OF ORANGE PEEL WASTE BY SUPERCRITICAL CO₂ EXTRACTION: GC–MS AND RAMAN SPECTROSCOPIC CHARACTERIZATION

Orange peel is an abundant agro-industrial by-product and a valuable source of essential oil rich in terpenes, particularly D-limonene. This study aimed to develop and optimize a solvent-free supercritical CO₂ extraction process for the recovery of high-value essential oil from waste orange peel and to evaluate the influence of extraction conditions on the yield and chemical profile of the obtained extracts. Supercritical CO₂ extraction was performed at pressures of 10 and 12 MPa and temperatures of 40, 45, and 50 °C. The obtained extracts were characterized using GC–MS method and Raman spectroscopy to assess changes in their chemical composition associated with the processing conditions. Extraction yields ranged from 0.552 to 1.752%, demonstrating a clear influence of pressure and temperature on the amount and characteristics of the recovered extracts. GC–MS analysis revealed D-limonene as the predominant compound in all samples, accounting for 92.7–96.7% of the total composition, while other mono- and sesquiterpenes were detected in lower amounts. Raman spectra confirmed the terpene-rich profile of the extracts and showed characteristic bands associated with D-limonene and other unsaturated hydrocarbon structures. Variations in Raman spectral profiles reflected changes in the relative contribution of lighter monoterpenes and higher-molecular-weight and oxidized components resulting from different extraction conditions. The consistency between Raman and GC–MS results demonstrate the potential of Raman spectroscopy as a rapid and non-destructive tool for comparative characterization and quality control of supercritical CO₂ extracts. Overall, the developed approach provides an environmentally sustainable route for converting orange peel waste into a high-value terpene-rich product with potential applications in the food, cosmetic, and pharmaceutical industries.

Keywords: Supercritical CO₂ extraction, orange essential oil, GC–MS analysis, Raman spectroscopy, waste valorization
Acknowledgements: This work was supported by the Ministry of Science, Technological Development and Innovation of the Republic of Serbia (Contracts No. 451-03-33/2026-03/200135 and 451-03-33/2026-03/200287) and the Western Balkans Innovation Voucher Programme (WBIV Application No. 09-2789; Contract No. 09-1007), within the Horizon Europe SPIN project (Grant Agreement No. 101058873).

Speaker: Mina Volić Ollier (University of Belgrade, Innovation Centre of the Faculty of Technology and Metallurgy)

17:20 DETERMINATION OF MICROELEMENTS IN CENTAURIUM UMBELLATUM GILIB. HERB

Introduction: The Centaurium umbellatum Gilib. is an healing plant for a sick stomach. It works primarily to prevent fermentation and stimulates the stomach function, intestines and salivary glands. It also works in case of insufficient secretion of sodium acid. It’s application improves the function of the stomach and intestines.1
Material and Method: In this work was used a sample of commercially available tea, that is, herb of Centaurium umbellatum Gilib. produced in Gadžin Han, Serbia by company EKOLIFE M.D. Plus. It was prepared in a microwave digestion device, and the qualitative and quantitative determination of microelements was performed using the ICP-OES method.2
Results and Conclusion: The content of all the 12 microelements determined is given in descending order [mg/kg]: К (7862), Cа (2298), Мg (1835), Na (1638),Fe (303), Al (249), Si (131), Zn (32.4), Mn (29), Ba (20.4), Cu (8.3) and Ni (6.11). Elements such as: As, Be, Cd, Co, Cr and Pb were not detected in the tested sample.
Acknowledgement: The authors are grateful to Republic of Serbia—Ministry of Science, Technological Development and Innovation, for financing the scientific research work numbers: 451-03-33/2026-03/200133 and 451-03-34/2026-03/200124, University of Niš, Faculty of Technology.

Keywords: Centaurium Umbellatum Gilib., ICP-OES method, microelements.

References:
(1) Guedes, L.; Reis, P. B. P. S., Machuqueiro, M.; Ressaissi, A.; Pacheco, R.; Serralheiro, M.L. Bioactivities of Centaurium erythraea (Gentianaceae) decoctions: Antioxidant activity, enzyme inhibition and docking studies. Molecules. 2019, 22, 3795. https://doi.org/10.3390/molecules24203795
(2) Santos, A. F.; Matos, R. A.; Andrade, E. M. J.; dos Santos, W. N. L.; Magalhães, H. I. F.; Costa, F. N.; Korn, M. G. A. Multielement determination of macro and micro contents in medicinal plants and phytomedicines from Brazil by ICP OES." J. Braz. Chem. Soc. 2017, 28, 376−384. https://doi.org/10.5935/0103-5053.20160187

Speaker: Milena Miljkovic

Milena Miljkovic SCTM 2026 e-Poster Abstract 1.pptx

17:25 DETERMINATION OF POTENTIALLY TOXIC ESSENTIAL ELEMENTS IN THE FLOWER OF HYPERICUM PERFORATUM L.

Introduction: The Hypericum perforatum L. has multiple healing properties. It is recommended for cleaning wounds and blood. Because of it’s pain-relieving and astringent properties it found usage as wounds cleaner, additionally, excellent medicine for nerves and works to reduce spasm as well as dissolving mucus. It’s essential oil is highly recommended.1
Material and Method: In this work was used a sample of commercially available tea consisted of Hypericum perforatum L. flowers. It was produced in Gadžin Han, Serbia by company EKOLIFE M.D. Plus. It was prepared in a microwave digestion device, and the qualitative and quantitative determination of microelements was performed using the ICP-OES method.2
Results and Conclusion: The content of 6 out of 10 potentially toxic microelements is given in descending order [mg/kg]: Mg (2058), Fe (68), Zn (39.7), Mn (19.4), Cu (9.6) and Ni (2.3). Elements such as: Mo, Se, Cr and B were not detected in the tested sample.
Acknowledgement: The authors are grateful to Republic of Serbia—Ministry of Science, Technological Development and Innovation, for financing the scientific research work numbers: 451-03-33/2026-03/200133 and 451-03-34/2026-03/200124, University of Niš, Faculty of Technology.

Keywords: Hypericum perforatum L., ICP-OES method, microelements.

References:
(1) Klemow, K. M.; Bartlow, A.; Crawford, J.; et al. Medical Attributes of St. John’s Wort (Hypericum perforatum) In: Benzie IFF, Wachtel-Galor S, editors. Herbal Medicine: Biomolecular and Clinical Aspects. 2nd edition. Boca Raton (FL): CRC Press/Taylor & Francis; 2011. Chapter 11. Available from: https://www.ncbi.nlm.nih.gov/books/NBK92750/
(2) Santos, A. F.; Matos, R. A.; Andrade, E. M. J.; dos Santos, W. N. L.; Magalhães, H. I. F.; Costa, F. N.; Korn, M. G. A. Multielement determination of macro and micro contents in medicinal plants and phytomedicines from Brazil by ICP OES." J. Braz. Chem. Soc. 2017, 28, 376−384. https://doi.org/10.5935/0103-5053.20160187

Speaker: Milena Miljkovic

Milena Miljkovic SCTM 2026 e-Poster Abstract 2.pptx

17:30 Assessment of Hemolysis Effects on Potassium and Lactate Dehydrogenase Measurements and Validation of a Hemolysis Index-Based Correction Model

Hemolysis is a common preanalytical source of interference that affects laboratory test results, particularly potassium (K) and lactate dehydrogenase (LDH) measurements [1,2]. This study investigated the impact of hemolysis on K and LDH results in routine laboratory practice and evaluated the performance of a hemolysis index (HI)-based correction method [3].
A retrospective analysis was performed using anonymized data generated by a Roche Cobas analyzer. Potassium, LDH, sodium (Na), and corresponding HI values were evaluated. Linear regression analyzed was used to assess the relationship between hemolysis and analyte concentrations. Regression-based correction models were subsequently applied to estimate and reduce hemolysis-induced analytical bias. The correction models were derived from routine clinical samples and therefore reflect real-world laboratory conditions.
A total of 111 serum samples were included in the study. Higher HI values were significantly associated with increased potassium concentrations (R² = 0.224, p < 0.001) and LDH activity (R² = 0.088, p = 0.002), whereas sodium showed no significant correlation with HI (R² = 0.002, p = 0.623). Potassium concentrations differed significantly across hemolysis categories (ANOVA, p < 0.001), increasing from 4.03 mmol/L at HI 0–10 to 4.63 mmol/L at HI >60. LDH activity increased from 279.9 to 402.6 U/L across the same categories. Application of the correction models substantially reduced these differences, with potassium differences decreasing from 0.60 to 0.04 mmol/L and LDH differences from 122.7 to 4.0 U/L.
These findings confirm the significant impact of hemolysis on potassium and LDH measurements and indicate that locally derived HI-based correction models may improve the interpretation of hemolyzed samples in routine laboratory practice.

Keywords: hemolysis, hemolysis index, potassium, LDH, analytical interference, clinical biochemistry, regression analysis, correction model

References:
1. Lippi G, Plebani M. Clin Chem Lab Med. 2012;50(3):393–401.
2. Koseoglu M, Hur A, Atay A, Cuhadar S. Biochem Med (Zagreb). 2011;21(1):79–85.
3. Lippi G, Cadamuro J, von Meyer A, Simundic AM. Clin Chem Lab Med. 2018;56(5):718–727.

Speaker: Mr Vlatko Bozhinoski

17:35 Short discussion

17:45 Development and optimization of an HPLC-UV-DAD method for simultaneous quantification of cefixime and sodium benzoate in oral suspension

Antibiotics, particularly cephalosporins, represent an importat group of drugs with wide application in modern medicine. Cefixime, a semisystetic third generation cephalosporin, is commonly used in the form of an oral suspension, where sodium benzoate is used as a chemical preservative. Existing internal quantification procedures are based on separate analytical methods employing different chromatographic conditions due to the differing nature of the active substance and the preservative.
The aim of this study is development, optimization and validation of a simple, rapid, sensitive and specific HPLC method for simultaneous determination of cefixime and sodium benzoate in oral suspensions. Several HPLC and UHPLC columns were evaluated, with detailed assessment of their performance in terms of resolution, efficiency, stability and durability. The results demonstrated that the UHPLC columns, although enabling faster analysis, do not provide sufficient robustness when analyzing a complex, sugar-rich matrix, like the oral suspension, which limits their suitability for routine quality control applications. The HPLC Waters XBridge C18 column proved to be the most appropriate, providing stable and reproducible chromatography, satisfactory resolution, appropriate peak shape and short analysis time. Furthermore, forced degradation studies under acidic, basic and oxidative conditions confirmed the specificity and selectivity of the developed method. In addition, the method was validated according to relevant ICH guidelines, including evaluation of linearity, accuracy, precision, specificity, filtration effects, stability, and robustness. 1, 2
The obtained results indicate that the proposed HPLC method is suitable for routine use in quality control laboratories as well as for regulatory purposes.

Speaker: Marijana Pejik (Alkaloid AD; Institute for Chemistry, Faculty of Natural Sciences and Mathematics)

Poster-Kongres-2026_HPLC-UV-DAD-cefixime-sodium benzoate-oral suspension_Marijana Pejik.pptx

17:50 ANALYTICAL VERIFICATION OF A PHARMACOPOEIAL HPLC METHOD FOR RELATED SUBSTANCES IN METAMIZOLE SODIUM MONOHYDRATE

Metamizole sodium monohydrate is a widely used non opioid analgesic and antipyretic, for which effective control of related substances is essential to ensure product quality. Although pharmacopoeial HPLC methods are established for this purpose, verification is required to confirm their suitability under routine laboratory conditions.
The aim of this study was to verify a pharmacopoeial HPLC method for the determination of related substances in metamizole sodium monohydrate. Method verification was performed in accordance with Ph. Eur. General Chapter 5.26, with evaluation of precision, specificity, and limit of quantification. Method precision was assessed using six independent samples, yielding a relative standard deviation (RSD) of the main peak area not exceeding 10 %. System precision, determined by six injections of the reference solution, demonstrated RSD ≤ 5%. Specificity was confirmed by chromatographic separation of the active substance from relative impurities with no observed interference at the retention time of the principal peak. The limit of quantification complied with the Ph. Eur. reporting shreshold, providing a signal-to-noise ratio of approximately 10:1 and acceptable precision (RSD ≤ 10 %).
The results of the verification study confirm that the pharmacopoeial HPLC method is suitable for its intended use in the routine quality control. This study supports reliable method implementation in quality control environment and contributes to compliance with pharmacopoeial and regulatory requirements for impurity profiling.
Keywords: Metamizole sodium monohydrate, specificity, precision, limit of quantification.
References:
1. European Pharmacopoeia Commission, European Pharmacopoeia, Council of Europe, Strasbourg, current edition: General Chapter 5.26, Verification of pharmacopoeial procedures.

Speaker: Sara Petreska (ALKALOID AD Skopje)

Poster_Method verification of metamizole sodium_Sara Petreska.pptx

17:55 Application of Counter-propagation Artificial Neural Networks in prediction of marbofloxacin, clotrimazole and dexamethasone concentrations in Otoxolan ear drops, suspension for dogs

Marbofloxacin is a potent antibiotic synthesized for veterinary use and treatment of advanced infections, which is often dosed in combination with other substances such as clotrimazole and dexamethasone. UV/Vis spectrophotometry, with its widespread and available instrumentation in research and testing laboratories, along with simple sample preparation, offers rapid analysis, which enables its application in quality control of pharmaceutical and veterinary preparations.
But simultaneous determination of these three compounds without prior separation can be challenging due to extensive overlapping spectra. In order to minimize the influence of the overlapping spectra on the results, principal components (PCs) extracted from the original UV spectra were used for the training of counter-propagation artificial neural networks (CPANN). The performances of the CPANN models were examined by (1) changing the number of principal components used for training as well as (2) the relative importance of the selected PCs. Cross-validation was used for control of the generalization performances of the CPANN models.
The developed models have excellent predictive performance for all three compounds with simultaneous quantification of marbofloxacin and clotrimazole with correlation coefficients of 0.99 for calibration and dexamethasone with a correlation coefficient of 0.95.
The results presented in this work demonstrate that analyzing complex mixtures is achievable using inexpensive instrumentation. The proposed UV spectrophotometric method assisted by CPANN represents a cost-effective tool for multicomponent pharmaceutical analysis, which has potential application in routine analysis in quality control laboratories while implementing artificial intelligence in analytical chemistry.

Keywords: Marbofloxacin, clotrimazole, dexamethasone, counter-propagation artificial neural networks, chemometrics, multicomponent analysis.
References:
1. M. Liu, The application of ultraviolet-visible spectrophotometry in pharmaceutical analysis, Appl. Comput. Eng. 159 (2025) 85–92. https://doi.org/10.54254/2755-2721/2025.23761
2. V. Cerdà, P. Phansi, S. Ferreira, From mono-to multicomponent methods in UV-VIS spectrophotometric and fluorimetric quantitative analysis – A review, TrAC Trends Anal. Chem. 157 (2022) 116772. https://doi.org/10.1016/j.trac.2022.116772

Speaker: Lina Bozhinovska

18:00 OPTIMIZATION OF AN HPLC METHOD FOR RISPERIDONE QUANTIFICATION FOR CLEANING VALIDATION PURPOSES

Risperidone is a widely used atypical antipsychotic acting primarily through antagonism of dopamine D₂ and serotonin 5-HT₂ receptors, indicated for the treatment of schizophrenia, bipolar disorder, and related psychiatric conditions.1 Cleaning validation is a critical requirement in pharmaceutical manufacturing to prevent cross-contamination and ensure patient safety. This study focuses on the optimization of the swabbing procedure and HPLC conditions for risperidone cleaning validation.
A key aspect of swab method development is the selection of an appropriate extraction medium that ensures high and reproducible recovery from equipment surfaces. Due to its potency, even trace residues of risperidone may lead to cross-contamination; therefore, sensitive and reliable analytical methods are required for its quantification in cleaning validation studies.
Risperidone is a weak base with pH-dependent solubility and significantly higher solubility under acidic conditions. In this study, recovery efficiency was evaluated using methanol and phosphoric acid–acidified methanol as swabbing media. The acidified medium significantly improved desorption from the swab matrix, achieving recoveries above the 80% acceptance criterion,² whereas unacidified methanol showed lower recovery.
The analysis was performed using a validated HPLC method optimized for cleaning validation. Improved separation of risperidone from adjacent peaks was achieved by increasing the proportion of inorganic mobile phase in combination with acetonitrile, which provided better resolution compared to methanol-based systems.
In conclusion, the use of an acidified extraction medium ensures robust and reproducible recovery, while the optimized HPLC method provides accurate and reliable quantification suitable for routine cleaning validation in risperidone manufacturing.

Speaker: Marijana Nikoloska

18:05 PERFORMANCE EVALUATION OF DIFFERENT HPLC COLUMNS IN ANALYSIS OF NICOTINE FROM E-LIQUIDS

The widespread use of electronic cigarettes highlights the need for accurate nicotine determination to ensure consumer safety and regulatory compliance. HPLC is widely used for nicotine analysis; however, chromatographic performance depends heavily on the stationary phase. To address this, this study compares three HPLC column chemistries for nicotine determination in a commercially available e-liquid from the Macedonian market: an end-capped C18 column (Purospher® Star RP18e), a conventional C8 column (Hypersil BDS C8), and a phenyl-hexyl column (ZORBAX Eclipse Plus Phenyl-Hexyl). Analyses were performed on a Nexera LC-40 DAD system using acetonitrile and 1% triethylamine in water (pH 7.0) (88:12, v/v) as mobile phase, at 1.0 mL/min, 30 °C, 260 nm, and 10 μL injection volume. The end-capped C18 showed the best performance, providing the highest efficiency (NTP = 8409) and optimal peak symmetry (tailing factor 1.1), likely due to reduced silanol interactions. The phenyl-hexyl column showed intermediate performance, whereas the C8 column exhibited peak fronting, possibly due to its lower carbon load and/or different end-capping chemistry. The method demonstrated excellent linearity (r² = 0.9999), low detection and quantification limits (LOD=0.0098 mg/mL; LOQ=0.0298 mg/mL, respectively), and high repeatability (RSD<0.3%). The results identify the end-capped C18 column as the most suitable choice for routine HPLC determination of nicotine in e-liquids.

Speaker: Mrs Zhaklina Poposka Svirkova (Institute for Public Health of the Republic of Macedonia, 50 Divizija No 6, 1000 Skopje, Republic of North Macedonia Faculty of Medical Sciences, Goce Delcev University, Krste Misirkov 10A, 2000 Stip, Republic of North Macedonia)

AEC-P15-Nicotine_SCTM_e-poster_filled.pptm

18:10 Internal Standards Use In Analyses of Cannabinoids

The dominant analytical techniques are of HPLC group of methods, predominantly with UV-PDA detecting for routne QC analyses in labs. Almost all of them are based on External Method of calculation of results. In this way, all standards and prepared samples are injected in replicates, which eliminate or minimize the errors of equipment malfunction or complexity and skills of analyst for sample preparation. Using of adequate Internal Standards substance may reduce these expenses by improvement of cost-efficiency of analysis by reducing number of injections, without jeopardizing the accuracy of results. We tested many substances and found 2 interesting of them, one more polar eluting as first significant peak on chromatogram, 4-methoxystilbene, and second is pentachlorobenzene, which in RP-C18 elution with acidified acetonitrile elutes near after the CBD molecule. The Response Factors Area/Conc were calculated for both Internal Standards and 5 main cannnabinoids, CBDA, CBD,CBN,THC and THCA, for plotting calculation linearity curve. If second IS2-pentachlorobenzene is used, monitoring is at UV=220nm, whie if we use IS1-4-methoxystylbene, Response Factor RF at 309-310nm gives slightly different results, whicg can be neglected if we use high peaks of Internal Standards. These supplication of of Internal Standards might simplified and create cheaper and Green-er methods.
Keywords: Cannabinoids, Quantification, HPLC, UV, PDA, Method, Internal Standard

References: , 1 PhEur 2026, 2 USP 2026, 3HPLC for Practicing Scientist(II);M.Dong.

Speaker: Dr Marjan Piponski (Quality Control Department in Pharmaceutical Company Replek Pharm)

18:15 Optimization of an analytical method for the determination of calcium and magnesium content using ICP technic

Optimization of an analytical method for the determination of calcium and magnesium content using inductively coupled plasma (ICP) technique

Stojance Kirovski1,2, Aleksandra Damjanoska1,2, Cveta Dolikjoska-Trajkova1, Stefan Radevski1, Liljana Velkovska1,2
e-mail: skirovski@alkaloid.com.mk

1Alkaloid AD Skopje, Blvd. Aleksandar Makedonski 12, Skopje, Republic of N. Macedonia

2Institute of Applied Chemistry and Pharmaceutical Analysis, Faculty of Pharmacy, Ss. Cyril and Methodius University in Skopje, Mother Tereza 47, Skopje, Republic of N. Macedonia

Lifecycle monitoring of analytical procedures described in ICH Q141 encompasses all activities from method development and validation to routine application and continual improvement. This study describes the optimization of an ICP analytical method for the determination of calcium and magnesium content during its lifecycle, based on continuous monitoring of result trends, which indicated the need for improved accuracy and robustness.
The optimization focused on critical sample preparation parameters, including filtration, calibration range, and the type of standards used. The results demonstrated that the type of filter (blue dot paper or regenerated cellulose (RC) 0.45 µm) does not significantly affect the accuracy or precision of the results, enabling the use of RC filters for routine analysis.
Extension of the calibration range improved linearity and correlation coefficients. However, discrepancies in assay values were observed when using externally sourced solution standards. This was successfully resolved by introducing in-house solid-state standards prepared from API materials, which ensured accurate recoveries (~100%) and improved agreement with expected results.
The optimized method was verified across multiple batches, placebo-spiked samples, and API combinations, demonstrating acceptable specificity, precision, accuracy, and reproducibility, including inter-analyst consistency.
Overall, this study illustrates how a lifecycle-based approach to method optimization can significantly enhance method performance and reliability. The use of in-house solid secondary standards combined with optimized sample preparation conditions ensures a robust and fit-for-purpose analytical method suitable for routine quality control.

Keywords: ICP, lifecycle management, method optimization, secondary standards, sample preparation, accuracy.
References:
1International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH). ICH Harmonised Guideline Q14: Analytical Procedure Development. 2023. Available from:https://database.ich.org/sites/default/files/ICH_Q14_Guideline_2023_1116.pdf

Speaker: Stojance Kirovski (Alkaloid AD Skopje)

Optimization of an analytical method for the determination of calcium and magnesium content using ICP technic.pptx

18:20 Comparative Evaluation of Laboratory Developed and Pharmacopoeial HPLC Methods for Cannabinoid Quantification

Cannabis is a complex phytochemical matrix rich in active cannabinoids such as Δ9 tetrahydrocannabinol (Δ9 THC) and Cannabidiol (CBD). Their accurate quantification is critical for quality control, patient safety, and regulatory compliance in medical cannabis.
A laboratory developed High Performance Liquid Chromatography – Diode Array Detector (HPLC DAD) method was compared with the pharmacopoeial reference HPLC method described in Ph. Eur. 11.5. The laboratory method featured an Agilent 1260 Infinity II HPLC system calibrated with a Cayman Chemicals 11-cannabinoid certified reference mixture; by comparison, the pharmacopoeial method incorporated Herbal Reference Standard (HRS) and Cannabidiol Chemical Reference Standard (CRS).
Both methods demonstrated comparable limit of detection (LOD) and limit of quantification (LOQ), confirming equivalent sensitivity. The laboratory developed method achieved a shorter analysis time of 13 minutes with satisfactory precision, whereas the pharmacopoeial method required 35 minutes but ensured superior reproducibility and regulatory reliability.
In summary, the laboratory developed method provides a rapid and efficient solution for routine analysis, while the pharmacopoeial reference method remains indispensable for compliance. Their complementary strengths support robust quality assurance in cannabinoid quantification.

Speaker: Dimitar Gusheski

18:25 Voltammetric study of caffeine: mechanism and analytical application

Caffeine is a naturally occurring purine alkaloid commonly found in coffee, tea, and cocoa, and is widely recognized for its stimulating effects on the central nervous system. Due to its widespread consumption and biological activity, accurate determination of caffeine content is essential in the food, pharmaceutical, and analytical chemistry industries for quality control, product labeling, and monitoring of commercial formulations [1,2]. Therefore, the development of reliable, sensitive, and cost-effective analytical methods for caffeine determination remains an important area of research.
In this study, a voltammetric method for the quantitative determination of caffeine was developed and validated using a boron-doped diamond (BDD) electrode as the working electrode and 0.1 M acetate buffer solution as the supporting electrolyte. Experimental conditions were optimized in order to enhance the sensitivity and selectivity of the analytical response. The electrochemical behavior of caffeine was investigated using the advantageous properties of BDD electrodes, including a wide potential window, low background current, excellent chemical stability, and high resistance to surface fouling. The developed method demonstrated excellent analytical performance, including good linearity, high sensitivity, satisfactory precision, and reproducibility. Furthermore, the method was successfully applied to the determination of caffeine in real samples, yielding accurate and reproducible results.
The obtained findings confirm that voltammetric techniques combined with boron-doped diamond electrode technology provide an efficient, rapid, and economical alternative to conventional analytical methods for routine caffeine analysis in commercial and pharmaceutical products.

Speaker: Monika Organdjieva (Alkaloid AD Skopje)

Poster_Voltammetry of caffeine_Kongres 2026_M.Organdjieva.pptx

18:30 HUMAN BIOMONITORING OF ORGANOCHLORINE PESTICIDES AND POLYCHLORINATED BIPHENYLS IN BREAST MILK: OPTIMIZATION OF ANALYTICAL PROCEDURES AND TRACE-LEVEL DETERMINATION

Human biomonitoring is an important approach for assessing human exposure to environmental contaminants and evaluating potential health risks associated with persistent organic pollutants (POPs). Among the most relevant POPs are organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), which are characterized by their persistence, bioaccumulation potential, and ability to transfer from mother to infant through breastfeeding.
This study aimed to develop and optimize an analytical procedure for the determination of selected OCPs and PCBs in human breast milk and to apply the optimized method to samples collected from breastfeeding mothers in North Macedonia. Due to the complexity and high lipid content of the matrix, different extraction, clean-up, and concentration procedures were systematically evaluated. The optimized method was subsequently validated by assessing key analytical performance parameters, including linearity, precision, recovery, limits of detection and quantification, reproducibility, and matrix effects.
Breast milk samples were collected from 30 breastfeeding mothers residing in different cities across North Macedonia. Prior to participation, informed consent was obtained from all mothers. In addition, participants completed a structured questionnaire designed to collect demographic information, lifestyle characteristics, dietary habits, and potential sources of environmental and pesticide exposure. Samples were stored at −20 °C until analysis.
Тhe determination of OCPs and PCBs was performed using gas chromatography coupled with an electron capture detector (GC–ECD). Data processing and statistical evaluation are currently ongoing and will provide valuable information on the occurrence of these contaminants in breast milk, potential exposure patterns, and factors influencing their presence in the studied population. The findings are expected to contribute to the limited data available on human exposure to POPs in North Macedonia and support future biomonitoring initiatives.

Keywords: Biomonitoring, POPs, breast milk, optimization, validation.

Speaker: Stefan Kirovski (Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss. Cyril & Methodius University in Skopje)

16:45 → 18:45 Parrallel E-poster Presentations (1S): Car Samoil Hall

16:45 Electrodeposition of Metals from Lunar Regolith Dissolved in Reline

To enable a sustainable human presence on the Moon, it is essential to use local resources safely and economically to access strategic metals1. This study evaluates the potential of deep eutectic solvents (DESs) for dissolving and electrochemically extracting metals from lunar regolith simulant. Lunar regolith simulant, representing Lunar Mare Soil (LMS-1), is an abundant and easily accessible material on the Moon2. LMS-1 was dissolved in freshly prepared reline (ChCl:Urea) by mechanical stirring at 250 rpm for 10 h at 70 °C under an argon atmosphere. The solubility of the oxides was determined using inductively coupled plasma–optical emission spectrometry (ICP–OES). In reline, Al₂O₃ showed a solubility of 0.4 wt%, SiO₂ reached 0.98 wt%, Cr₂O₃ exhibited the highest solubility at 14.6 wt%, followed by FeOₜ at 2.27 wt% and MgO at 4.1 wt%. Electrochemical measurements and electrolysis experiments were carried out in the supernatant solution using a three-electrode system: gold (Au) as the working electrode, platinum (Pt) as the counter electrode, and a platinum wire (Pt, 2 mm diameter) as the quasi-reference electrode. The equilibrium potentials of the metals were measured and correlated with the order in which the metals should be deposited on the cathode. Electrochemical investigations using cyclic voltammetry and square-wave voltammetry evaluated a highly complex system involving multiple multivalent redox processes. Selective metal recovery was subsequently achieved by potentiostatic electrolysis by adjusting the electrode potential. At more positive deposition overpotentials, the deposit was composed mainly of Si, whereas Al, Cr, and Fe, along with Si, were electrodeposited at more negative potentials, demonstrating controlled potential-dependent metal separation. These results demonstrate the possibility of controlled and selective metal deposition directly from DES electrolytes.
Keywords: Choline Chloride-Urea, Silicon, Lunar Mare Soil, Electrodeposition
Acknowledgement: Research was supported by the Science Fund of the RS, #Grant No. 270, Applying advanced product intellectual properties and industrialization workflows to innovative fundamental research ideas in the area of rare earth electrochemical recovery –REMEDIS. V.S.C. and N.M.P. acknowledge the financial support from the Ministry of Science, Technological Development and Innovation of the RS (Contract No: 451-03-33/2026-03/200026).
References:
1. Maes, M.; Gibilaro, M.; Chamelot, P.; Chiron, C.; Chevrel, Pinet, P.C.; Massot, L.; Favier, J.J.; Planet. Space Sci., 2024, 242, 105854. https://doi.org/10.1016/j.pss.2024.105854.
2. Schwandt, C., Hamilton, J.A., Fray, D.J., Crawford, I.A., Planet. Space Sci., 2012, 74, 49–56. https://doi.org/10.1016/j.pss.2012.06.011.

Speaker: Vesna Cvetković (Department of Electrochemistry, Institute of Chemistry, Technology and Metallurgy, University of Belgrade)

16:50 Deposition of Dysprosium from Ethaline deep eutectic solvent

Rare earth elements (REEs), particularly dysprosium (Dy), are critical for development of future clean energy technologies. However, their recovery from end-of-life (EOL) NdFeB magnets faces significant challenges and has not been widely implemented at the industrial scale. Improving resource efficiency requires the development of recycling and recovery methods for REEs from EOL waste using cost-effective and environmentally friendly technologies. Deep eutectic solvents (DESs) present a promising alternative due to their low cost, simple preparation, low toxicity, and wide electrochemical window1, compared with conventional high-temperature molten salt electrolytes commonly used for electrolysis.
In this study, the electrochemical reduction and deposition of Dy(III) were investigated for the first time, in a choline chloride and ethylene glycol (1:2, ChCl:EG) deep eutectic solvent (Ethaline) at 70 °C using a gold working electrode. Cyclic voltammetry (CV) and square wave voltammetry (SWV) in 0.1 M DyCl₃–Ethaline electrolyte revealed a single-step, irreversible three-electron transfer process for the reduction of Dy(III) to Dy(0). Potentiostatic deposition at −0.800 V vs. Ag for 4 h produced deposits whose morphology, elemental composition, and surface chemical states were characterized by SEM, EDS, and XPS. The combined analyses confirmed the formation of metallic dysprosium. These results demonstrate the potential of Ethaline as an environmentally friendly medium for the low-temperature electrodeposition of rare earth metals. This approach offers a sustainable pathway for recovering critical materials from EOL and contributes to the development of greener recycling technologies.
Keywords:Choline Chloride-Ethylene Glycol, Dysprosium, Rare earth elements, Deposition
Acknowledgement: This research was supported by the Science Fund of the Republic of Serbia, #Grant No. 270, Applying advanced product intellectual properties and industrialization workflows to innovative fundamental research ideas in the area of rare earth electrochemical recovery – REMEDIS. V.S.C. and N.M.P. acknowledge the financial support received from the Ministry of Science, Technological Development and Innovation of the RS (Contract No: 451-03-33/2026-03/200026).
References:
1. Cvetković, V.S.; Petrović, N.M.; Nikolić, N.D.; Jovićević, J.N.; Influence of Cu(II) Ion Concentration on Copper Electrodeposition from Deep Eutectic Solvent on Inert Substrate, Metals, 2025, 15, 716. https://doi.org/10.3390/met15070716.

Speaker: Dr Nataša Petrović (Institute of Chemistry, Technology and Metallurgy, National Institute of the Republic of Serbia, University of Belgrade)

16:55 Ternary thin film catalyst obtained by galvanic displacement method for formic acid electrooxidation

Pollution from fossil fuels resulting from industrialization, urbanization and technological progress greatly affects the environment and human health. Thus, the main challenge confronting both the scientific community and humanity is to reduce reliance on fossil fuels by shifting energy production and consumption to renewable energy sources. The development of catalysts for the electrooxidation of small organic molecules, such as formic acid, requires an optimal balance between cost and catalytic activity and stability. Platinum (Pt) remains among the most effective choices for formic acid electrooxidation (FAO), despite its high cost, limited availability, and susceptibility to carbon monoxide poisoning. Catalysts incorporating multiple active metals can significantly enhance performance while reducing the use of Pt.
In this study, platinum-based catalysts were produced using a galvanic displacement method, in which platinum and iridium (Ir) replace nickel. The thin film PtIr@Ni catalyst was obtained via a two-step spontaneous galvanic displacement process. Following synthesis, the catalyst underwent thermal treatment to further improve activity and stability. The activity of the catalysts was tested in the formic acid electrooxidation reaction, while the influence of thermal treatment on the surface morphology was monitored using atomic force microscopy (AFM).
Catalysts obtained using this approach, in addition to being very active and stable, contain extremely small amounts of precious metal, thereby lowering the overall cost and bringing fuel cell technology closer to full commercialization.

Speaker: Dusan Tripkovic (Institute of Chemistry, Technology and Metallurgy-Department of Electrochemistry)

17:00 Electrochemical Sodium Storage in Hard Carbons Derived from Industrial Lignin Waste

Hard carbons derived from renewable biomass are promising anode materials for sodium-ion batteries due to their low cost, sustainability, and favorable electrochemical properties. In recent years, in line with the increasingly widespread circular economy model, household biowaste has been used as raw material for the preparing of hard carbon [1].
In this work, we demonstrate industrial waste with high lignin content as precursors for the synthesis of hard carbons. Kraft lignin (from pulp and paper industry) and technical hydrolysis lignin (from filamentous yeast production) were pyrolysed on two temperature steps - at 800 and 1300 °C. The obtained materials were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA-TG) and electrochemical techniques. The electrochemical performance of the lignin-derived hard carbons was evaluated in sodium half-cells using galvanostatic charge–discharge cycling in two mode: “constant current” and “constant current – constant voltage”, cyclic voltammetry, first sodiation discharge, first irreversible capacity, cycling stability. The results show reversible sodium storage, good cycling stability, and the influence of lignin precursor type on the structural and electrochemical properties of the materials. The observed differences are associated with variations in carbon disorder and pore structure. The study highlights the potential of industrial lignin waste as sustainable precursors for hard carbon anodes in next-generation sodium-ion batteries.

Speaker: Tsvetelina Gerasimova (Bulgarian academy of sciences - Institute of general and inorganic chemistry)

17:05 Deciphering sodium-ion insertion mechanism into hard carbon by ex-situ EPR spectroscopy

Since the hard carbons (HCs) has emerged as promising negative electrode materials for sodium-ion batteries, numerous research has been done on the factors impacting their electrochemical performance. Nevertheless, one of the most debatable question remains the sodium-ion insertion mechanism. Recently, we report electron paramagnetic resonance (EPR) spectroscopy as a comprehensive method to monitor the interaction of sodium into carbons derived from spent coffee grounds and used as electrodes in sodium-ion cells [1].
Herein, we applied the ex-situ EPR spectroscopy to monitor the sodium-ion insertion into hard carbons derived from lignin precursors. As precursors industrial biowaste was selected, i.e. kraft lignin and technical hydrolysis lignin. The HCs were prepared by pyrolysis at high temperatures (800 and 1300 oC) and under a constant Ar-flow. Depending on the biomass origin and synthesis temperature, the HCs show clearly distinguishable texture. The electrochemical insertion of sodium into hard carbons were carried out in model Na-cells consisting of sodium metal as counter electrode and in presents of carbonate-based sodium electrolyte (1M NaPF6:PC). At selected potential stages during the first electrochemical sodiation, the cells were stopped and ex-situ EPR spectroscopy was employed. The EPR analysis reveals the correlations between textural features - sodium intercalation - sodium cluster formation - storage performance. This insight into sodium storage mechanism can serve as a guiding point in the design of more efficient carbon electrode materials.

Speaker: Tsvetelina Gerasimova (Bulgarian academy of sciences - Institute of general and inorganic chemistry)

17:10 Sodium Ion Mobility in Carbon Decorated Na4Fe3(PO4)2P2O7 Electrode Material: Comparative Study

Sodium-ion batteries (SIBs) offer an efficient energy storage solution for large-scale applications. Na4Fe3(PO4)2P2O7 (NFPP) is recognized as a promising candidate for electrode material in SIBs: it is able to intercalate reversibly up to 3 moles of Na ions. The main disadvantage of NFPP is its very low electronic conductivity, which hinders the Na+ mobility. To increase NFPP conductivity, a conventional strategy involves its coating with various carbonaceous materials in an amount of about 10-15 wt. %. However, the presence of a large amount of electrochemically inactive carbonaceous additives in the electrode composition is a major contributor to the lower overall energy density of the battery cells, which is one of the most important characteristics for practical application.
To overcome the reduced energy density, the purpose of the present contribution is to decorate NFPP with carbon additives with a minimal amount of 1 wt. %: carbon black (CB) and reduced graphene oxide (rGO). The composites NFPP/CB and NFPP/rGO have been prepared by a dry-coating method. The galvanostatic/potentiostatic tests have been performed at 20 and 40 C in Na half-cells. Electrochemical performance has been evaluated in terms of capacity and cycling stability, while the origin of the kinetic response is studied by electrochemical impedance spectroscopy (EIS). The contributions of the Faradaic and capacitive reactions in NFPP/CB and NFPP/rGO have been compared. The effect of the carbon additive on the Na-ion diffusion has been studied by three electrochemical methods: EIS, cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT). The difference in the electrochemical behaviour of NFPP/CB and NFPP/rGO has been discussed based on the data for the electrolyte resistance (Re), electrolyte/electrode interfacial resistance (RSEI), and charge-transfer resistance (Rct). The results show a clear distinction in the role of the two types of carbon additives.

Keywords: Sodium-ion Batteries, Electrochemical Techniques, Sodium Diffusion Kinetics
Acknowledgement:
We acknowledge the project “Master” (KП-06-ДO02/3 dated 18.05.2023) and the infrastructure support of the contract “National Center of Excellence Mechatronics and Clean Technologies” (BG16RFPR002-1.014-0006) under “Research, Innovation and Digitization for Smart Transformation” program 2021-2027.

Speaker: Trajche Tushev (Institute of General and Inorganic Chemistry - BAS)

17:15 Еffect of Carbon Additives for Electrochemical Performance of Mixed Polyanion-Type Electrode Material NaFeVPO4(SO4)2 for Sodium-Ion batteries

The rising demand for energy makes the development of new high-performance energy storage systems a major concern. Sodium-ion battery technology is one of the best alternative to the lithium analogue due to the low cost and abundance of sodium which are critical issues for large-scale application. One of the challenges facing SIBs is the exploration of new cheap electrode materials with efficient electrochemical performances suitable for practical applications. This can be achieved through design of electrode materials that allow compositional diversity in combination with both cationic and anionic substitutions. Polyanionic electrode materials with NASICON type of structure fulfill the above requirements to a great extent.
The present work is focused on the electrochemical performance of a multi-electron material sodium-iron-vanadium-phosphate-sulfate (NFVPS) that combines two abundant transition metals having multiple oxidation states with two anionic groups in a stable NASICON structure. In addition, the sulfate substitution for phosphate is known to enhance the potential of the redox reactions thus increasing the power density. In order to enhance the capacity and long-term cycling stability, NFVPS was decorated with two carbon additives, reduce grapheme oxide (rGO) and carbon black (CB), using simple ball-milling treatment. The electrochemical tests of the two composites were performed in sodium half-cells in voltammetric and galvanostatic modes at 20 and 40 oC. The cycling voltammograms reveal reversible cathodic and anodic peaks ascribable to iron and vanadium redox couples. The CV-curve profile for NFVPS/rGO evidences for simultaneous occurrence of capacitive and Faradaic electrochemical reactions, while Faradaic reactions are predominant for the NFVPS/CB composite. The contribution of Faradaic and capacitive reactions in the two composites were estimated. The cycling stability (C/2 rate) and rate capability tests show that NFVPS/rGO outperforms NFVPS/CB at 20 and 40 oC. The storage performance of NFVPS/rGO is among the best performing iron-vanadium phosphates.

Keywords: Sodium-ion batteries, Electrochemical Performance, Multi-electron Reactions
Acknowledgement:
We acknowledge the project “Master” (KП-06-ДO02/3 dated 18.05.2023) and the infrastructure support of the contract “National Center of Excellence Mechatronics and Clean Technologies” (BG16RFPR002-1.014-0006) under “Research, Innovation and Digitization for Smart Transformation” program 2021-2027.

Speaker: Trajche Tushev (Institute of General and Inorganic Chemistry - BAS)

17:20 Peri-Annulated Diselenides as a Framework for High-Rate Organic Li/Na Electrodes

The utilisation of organic electrode materials (OEMs) as versatile redox-active hosts for lithium- and sodium-ion batteries is a recent development. The popularity of these materials is driven by their tunability, sustainability, and capacity to store both cations and anions within one framework. The structural flexibility inherent to these substances renders them far less sensitive to the ionic radius of the charge carrier in comparison to conventional inorganic intercalation hosts. This quality positions them as a particularly attractive proposition for use in sodium-ion batteries, where the larger size of Na⁺ frequently limits both diffusion and structural stability.
Here, we investigate the mechanism of bipolar redox reactions in naphthalimide (NI) derivatives when used as cathodes in lithium and sodium half-cells with ionic liquid electrolytes. To improve the low electronic conductivity, NI was composited with rGO.
Electrochemical tests were conducted in potentiostatic and galvanostatic modes within a range of potential windows spanning between 1.0-4.6 V. The results of the CV experiments demonstrate the bipolar nature of the studied NIs. The objective of the cyclic stability experiments is to ascertain the influence of the incorporated groups at the imide nitrogen and the halogen substituent in the naphthalimide core. The results demonstrate that the specific capacity of lithium cells stabilises after the 20th cycle, whereas that of sodium cells stabilises after the 5th cycle, irrespective of the halogen substituent. Furthermore, long-term cycling tests were conducted under conditions of high current loads. The investigation revealed that the specific capacity of the sodium electrolyte at a current load of 500 mA/g decreased marginally from 45 mAh/g to 35 mAh/g. This finding suggests that the cathode material exhibited consistent high-rate performance.

Speaker: Victoria Stoeva (Institute of General and Inorganic Chemistry (IGIC))

17:25 Composite of ZnO with reduced graphene oxide as anode for sodium-ion batteries

Sodium-ion batteries are a promising alternative to lithium-ion batteries. They use sodium, which is less expensive than lithium. However, developing high-capacity, stable anode materials is challenging. Zinc oxide (ZnO) has a wurtzite structure and a high theoretical capacity, but it exhibits poor conductivity during charge/discharge cycles and undergoes fast degradation. However, his ZnO nanoparticles functionalized with reduced graphene oxide (rGO) are promising anodes for sodium-ion batteries¹. The aim of our study is to investigate the role of rGO in improving the electrochemical parameters of ZnO and enhancing its performance as an anode in sodium-ion cells.
The electrochemical performance of ZnO/rGO composite electrodes was examined using sodium half cells with a standard electrolyte of 1 M NaPF6 in PC. Cycling voltammetry was recorded at different speeds ranging from 1 mV/s to 0.1 mV/s to determine redox reactions. The results show that the rGO/ZnO composite outperforms the individual ZnO component in terms of cycling stability and rate capability. Thus, our study emphasizes the importance of the synergistic effect between rGO and ZnO in enhancing the structural integrity and charge-transport kinetics of anode materials for sodium-ion batteries.

Keywords: ZnO, rGO, anodes for sodium-ion battery

Acknowledgments:
This work was supported by the infrastructure of the 'National Center of Excellence Mechatronics and Clean Technologies' contract (BG16RFPR002-1.014-0006) under the 'Research, Innovation and Digitization for Smart Transformation' program 2021–2027. We thank Robert Feher (Graphit Kropfmühl GmbH, Germany) for providing the rGO additive. N. Kaneva thanks the Bulgarian National Science Fund (BNSF) for the full financial support provided under project КП-06-Н89/07.

References:
[1] Liu, J., He, Z., Zhao, T., Wei, J., Hou,I., Song, Y., Wang, Y., Chemical Engineering Journal, 500, 2024, 157389, https://doi.org/10.1016/j.cej.2024.157389.

Speaker: Mr Trajce Trajkov (Department of General and Inorganic Chemistry, Faculty of Chemistry and Pharmacy, University of Sofia)

17:30 Rietveld Structural Analysis and Electrocatalytic Activity of GdMn0.5M0.5O3 (M = Cr, Fe, Co, Ni, Cu) Double Perovskites toward Hydroxide Oxidation and Hydrogen Evolution Reactions

GdMn0.5M0.5O3 (M = Cr, Fe, Co) double perovskites were synthesized via a glycine-assisted solution combustion method. Phase purity and crystal structure were confirmed by powder X-ray diffraction, while Rietveld refinement established the formation of single-phase orthorhombic structures within the Pnma space group, and Z = 4. Structural analysis revealed significant octahedral distortions, quantified through crystallochemical parameters including the global instability index.
Far-infrared spectroscopy (FIR) supported the structural results by showing characteristic metal–oxygen vibrational modes and systematic band shifts associated with lattice distortion. Scanning electron microscopy (SEM) revealed a porous combustion-derived morphology, while successive annealing treatments enhanced grain growth and microstructural homogeneity. Energy-dispersive X-ray spectroscopy (EDX) confirmed uniform elemental distribution close to the nominal composition.
Electrocatalytic performance was evaluated by cyclic voltammetry using perovskite modified paraffin impregnated graphite (PIGE) electrodes. The investigated materials exhibited composition-dependent activity toward hydroxide oxidation and hydrogen evolution reactions, with the Co-substituted sample showing the highest catalytic efficiency and good electrochemical stability.

Keywords: Perovskites, Solution combustion synthesis; Rietveld refinement; FIR, SEM/EDX, cyclic voltammetry

Speaker: Besarta Cheliku Ramadani (University of Tetovo)

17:35 Short discussion

17:45 Plasma Characterization and Matrix Effects in Hydrophilic Chia Seeds Studied by TEA CO2 Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) was employed to investigate plasma characteristics and matrix-induced analytical effects in hydrophilic chia (Salvia hispanica L.) seeds. Owing to their gel-forming polysaccharide matrix, chia seeds represent a structurally complex material that can significantly influence plasma formation and emission stability. Pressed pellet samples were analyzed under optimized TEA CO2 laser conditions, while elemental concentrations were validated by inductively coupled plasma–optical emission spectrometry (ICP–OES). Quantitative calibration was performed for Ca, Fe, Zn, and Mg using analyte-to-internal standard intensity ratios, yielding high linearity with correlation coefficients (R2) of 0.989 (Ca), 0.991 (Fe), 0.997 (Zn), and 0.989 (Mg). In addition to the calibrated elements, emission lines of major constituents (P, K, Ca, Mg) and trace elements (Ba, Sr, Ti, Cu, Al, Si) were clearly detected. Plasma diagnostics revealed an electron temperature of ~ 10,000 K and an electron number density of ~ 4 × 1016 cm-3, confirming stable plasma conditions despite pronounced matrix effects. The obtained results are consistent with previously developed LIBS methodologies for plant-based matrices1 and further demonstrate that TEA CO2 LIBS provides reliable multielemental quantification in hydrophilic food materials.

Speaker: Dr Dragan Ranković (VINCA Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, Mike Alasa 12-14, 11001 Belgrade, Serbia)

28-SCTM-e-poster Chia Seeds.pptx

17:50 Where do Metallic Impurities Come From in Industrial Gases Detected by Laser-Induced Plasma Spectroscopy?

This work builds on the previous study, which documented the initial detection of metallic impurities (vanadium and possibly Fe and Cu) in commercially available argon gas supplied in steel cylinders 1. In the present study, the laser-induced gas plasma was spectroscopically analyzed over the spectral range 250-550 nm in argon (5.0), helium (4.6), and air at atmospheric pressure. Because vanadium exhibits a prominent spectrum in argon plasma, as identified in the NIST database 2, its presence is strongly confirmed, as indicated lastly1. Similarly, the iron line-rich spectrum overlaps with the vanadium spectrum, making reliable identification difficult but highly likely, since no other elements were identified within those ranges. For example, a number of iron lines are registered around 240 nm, and vanadium shows lines around 300 nm and 450-500 nm, where only vanadium lines are identified. Upon further examination of the updated spectra, two additional elements are detected in argon gas: copper and zinc. Those elements exhibit multiple lines across broad spectral ranges, especially copper. Zinc is identified by several lines, primarily through a persistent line at 328 and 330 nm. Compared to argon plasma, helium and air plasmas result in an almost empty line spectrum.
The main question is: what is the origin of the metal impurities detected in argon? If present, their concentrations must be extremely low yet detectable, so they can be quantified by laser-induced breakdown plasma spectroscopy.
How does metal contaminate argon gas but not helium? As we stated earlier, this could be a consequence of the purification process during gas production 1. Now, another possible reason is the so-called dealloying process, or leaching 3.

Speaker: Milovan Stoiljkovic (principal research fellow)

28-SCTM-e-poster Ohrid 2026.pptx

17:55 Structural and Spectroscopic Data of Some Aquachloro Complexes

This work investigates the structural and spectroscopic characteristics of water molecules in aquachloro complexes in the solid state and analyzes the dynamics of hydrogen bonding in crystalline environments. Structural and spectroscopic data from selected aquachloro complexes were systematically extracted from crystallographic publications and comparatively analyzed. Methodologically, the study combines a review of the fundamental principles of solid-state chemistry, with particular emphasis on hydrogen bonding in confined systems, and statistical processing of structural parameters (bond lengths and coordination geometry) together with spectroscopic data in order to establish spectrum–structure correlations. The analysis highlights how confined environments in solid-state systems influence the structural flexibility of water molecules and their bonding interactions. The conclusions emphasize the role of lattice geometry in determining the efficiency of hydrogen bonding, thereby providing insights into the design of crystalline materials with controlled hydration properties.

Speaker: Mr Nikola Bojcevski (Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University in Skopje, Arhimedova 5, Skopje, Macedonia)

18:00 Interpreting Positive and Negative IR Reflectance-Absorbance Intensities in 2T2D Correlation Spectroscopy of Siloxane Films on Silicate Glass

Katerina Kraljevska, Vladimir Ivanovski
e-mail: kraljevskakaterina0808@gmail.com

Ss. Cyril and Methodius University in Skopje, Faculty of Natural Science and Mathematics, Arhimedova 5, 1000 Skopje, Macedonia

Organosilanes can be used to engineer silicate glass surfaces, creating water repellent coatings that enhance hydrophobicity without compromising transparency. The process involves forming a nanometric siloxane film and altering surface roughness to achieve hydrophobicity. In this work, glass substrates were modified with hydrolyzed or non-hydrolyzed 3 aminopropyltriethoxysilane (APTES). Contact angle measurements, calculated surface energy, AFM and Raman measurements demonstrated successful silanization of the surface1. We used two-trace two-dimensional correlation spectroscopy (2T2D-COS) as a tool in distinguishing the IR bands between the substrate silicate glass and the ultrathin nano-film of siloxane formed on its surface. For that purpose, both, originally recorded IR Specular Reflectance spectra (IR-SR) and calculated IR Reflectance-Absorbance (IR-RA) spectra were used for creating the 2T2D-COS maps. While 2T2D-COS obtained from IR-SR can be used as an independent method for localizing the film band’s wavenumber, compared to IR-RA spectra, the 2T2D-COS obtained from IR-RA has the advantage of comparing the structure of two siloxane films2. However, since the IR-RA spectra can have positive and negative bands (contrary to the IR-SR), this has its impact on the interpretation of the positive and negative peaks in the 2T2D-COS maps. This work tries to turn attention on the consequences if this fact is not taken into account and gives solution to the problem.
Keywords: silicate glass, hydrophobicity, APTES, IR-SR, IR-RA, 2T2D COS

References:
1 V. Ivanovski, G.A. Mousdis, V. Likodimos, T. Deckert-Gaudig, T.A. Shaik, V. Deckert, Th.G. Mayerhöfer, J. Popp, A. Ivanovski, Investigation of thin siloxane films on silicate glass obtained from low concentration 3-aminopropyltriethoxysilane using reflectance FTIR and Raman confocal in-depth measurements, Colloids Surf. A Physicochem. Eng. Asp. 742 (2026) 140432. https://doi.org/10.1016/j.colsurfa.2026.140432
2 V. Ivanovski, Th.G. Mayerhöfer, 2T2D-correlation analysis of infrared specular reflectance and ratio-reflectance spectra for investigating siloxane nanofilms on silicate glass substrates, Spectrochim. Acta A Mol. Biomol. Spectrosc. 336 (2025) 126038. https://doi.org/10.1016/j.saa.2025.126038
strong text

Speakers: Katerina Kraljevska, Dr Vladimir Ivanovski

18:05 TEMPERATURE-DEPENDENT STRUCTURAL DYNAMICS OF MOLECULARLY ENGINEERED INSULIN DETEMIR REVEALED BY X-RAY DIFFRACTION AND TWO-DIMENSIONAL CORRELATION ANALYSIS OF INFRARED AND RAMAN SPECTRA

We report a comprehensive study of the structure, molecular organization, conformational heterogeneity, supramolecular packing and thermally-induced dynamics of insulin detemir, a long-lasting engineered insulin analogue obtained by removal of ThrB30 and covalent attachment of myristic acid chain to LysB29. Powder X-ray diffraction, temperature-dependent Fourier-transform infrared and Raman spectroscopy and generalized two-dimensional correlation analysis (GEN-2DCOS), together with moving-window (MW) and perturbation-correlation moving window (PCMW) 2DCOS approaches were employed to probe temperature-induced structural transformations.
The combined analyses reveal coupling between conformational changes of the protein backbone and rearrangements of the myristic acid chain, providing insights into the interplay between -helical backbone adjustments, and stabilization of hexameric assemblies. The sequence of temperature-induced structural changes was established through joint analysis of synchronous and asynchronous two-dimensional correlation spectra, enabling identification of processes associated with partial unfolding, intermolecular association and fatty acid packing. Furthermore, the applied methodology provides information on the rigidity of the disulfide bonds, their rearrangements in the course of aggregation, as well as on the propagation of conformational changes through the molecule.
The results demonstrate how conformational adaptations of the insulin backbone are linked to intermolecular self-assembly and crystallization phenomena, highlighting the utility of advanced two-dimensional correlation approaches for elucidating complex relationships between structure and dynamics in engineered protein pharmaceuticals.

Keywords: insulin detemir, protein conformational dynamics, self-association, two-dimensional correlation spectroscopy (2DCOS), moving-window (MW) 2DCOS, perturbation-correlation MW 2D COS, temperature-dependent structural dynamics.

Speaker: Ljupcho Pejov (Institute of Chemistry, Faculty of Natural Sciences and Mathematics, SS Cyril and Methodius University, 1000 Skopje, Republic of North Macedonia)

18:10 THEORETICAL IRMPD SPECTROSCOPY OF PROTONATED GLYCINE TAGGED WITH HYDROGEN AND HELIUM

Protonated glycine constitutes one of the most extensively investigated model systems in gas-phase ion chemistry due to its fundamental relevance for understanding proton localization, conformational flexibility, as well as intra- and intermolecular hydrogen-bonding interactions in biomolecular ions. Owing to its structural simplicity and rich vibrational behavior, it provides an ideal platform for developing and validating theoretical methodologies aimed at interpreting high-resolution infrared spectroscopic data. In particular, the combination of computational chemistry and infrared multiple-photon dissociation (IRMPD) spectroscopy has emerged as a powerful framework for establishing detailed relationships between structure and spectrum in isolated molecular ions.
In the present study, a comprehensive theoretical investigation of protonated glycine and its weakly bound complexes with helium and molecular hydrogen is performed with the objective of elucidating the influence of molecular tagging on structural stability, vibrational dynamics, and predicted IRMPD spectral signatures. Special attention is devoted to the limitations of the harmonic approximation and the necessity of incorporating anharmonic effects for an accurate description of highly localized X–H stretching vibrations. The vibrational dynamics is analyzed beyond the purely harmonic regime, enabling a more realistic representation of frequency shifts, mode coupling, and energy-transfer pathways that contribute to multiphoton dissociation mechanisms. To account for the coexistence of multiple low-energy conformers, Boltzmann-weighted spectral averaging is applied, allowing thermodynamic populations to be incorporated into the theoretical spectra.
Comparative evaluation of the calculated spectra reveals that helium preserves the native structural characteristics of the ion to a large extent, whereas hydrogen induces measurable perturbations that are particularly pronounced in vibrational modes associated with protonated and hydrogen-bonded sites. Beyond the specific system investigated, the study illustrates the broader role of theoretical chemistry in supporting spectroscopic characterization of isolated biomolecular ions and in guiding future studies of structurally related systems.

Keywords: protonated glycine, quantum chemistry, IRMPD spectroscopy, anharmonic vibrations, conformational analysis, molecular tagging, potential energy surface, vibrational dynamics.

Speaker: Adela Asani (Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University in Skopje, North Macedonia)

18:15 Benchtop NMR as a Feasible and Reliable Technique for Detection of Honey Adulteration

Honey is a natural product produced by honey bees from floral nectar or honeydew secretions, highly valued for its nutritional and functional properties.1 Due to its high market value, honey is frequently adulterated with inexpensive sugar syrups or through indirect bee feeding practices, making the development of reliable methods for authenticity assessment and adulteration detection increasingly important.2 NMR have been developed during the last three decades for the detection of honey adulterants. However, these technique require highly trained stuff and special conditions. Compared to conventional high-field NMR systems, benchtop NMR spectrometers offer several advantages, including lower cost, compact size, easier operation, minimal maintenance requirements, and no need for liquid helium or other cryogens. Additionally, they enable rapid, non-destructive analysis on site, making them highly suitable for routine quality control and honey authenticity studies at honey collection points.3
Two different polyfloral honeys (pure – natural from beekeeper and adulterated – commercially purchased with adulteration history) were submitted to benchtop NMR analysis in order to demonstrate feasibility of benchtop NMR as a fast and easy-to-use method for adulteration determination.
The 1H NMR spectra revealed clear differences between the pure honey sample and the sample adulterated with sucrose. Significant increase of intensity of the sucrose signal (around 5.4 ppm) was observed in the adulterated sample.
These results demonstrate the potential of benchtop NMR spectroscopy as a rapid and non-destructive tool, and first of all a cheap method for detecting honey adulteration.

Keywords: honey, adulteration, benchtop NMR analysis.

References:
1) Codex Alimentarius Commission. Codex Standard for Honey (CODEX STAN 12–1981); Food and Agriculture Organization of the United Nations and World Health Organization: Rome, Italy, 2001.
2) Crăciun, M. E.; Parvulescu, O. C.; Donise, A. C.; Dobre, T.; Stanciu, D. R. Characterization and Classification of Romanian Acacia Honey Based on Its Physicochemical Parameters and Chemometrics. Sci. Rep. 2020, 10 (1), 20690.
3) Yu, H.-Y.; Myoung, S.; Ahn, S. Recent Applications of Benchtop Nuclear Magnetic Resonance Spectroscopy. Magnetochemistry 2021, 7 (9), 121.

Speaker: Vesna Cvetković (Department of Electrochemistry, Institute of Chemistry, Technology and Metallurgy, University of Belgrade)

18:20 Rapid authentication of salep in commercial products using VIS-NIR spectroscopy coupled by statistical methods

Salep powder, derived from dried tubers of wild terrestrial orchids, is a high-value ingredient used to prepare a thick, hot winter beverage valued for its many reported health benefits. However, products marketed as salep are often diluted, adulterated or falsified, unless specifically declared as pure, with low-cost ingredients such as sugars and starches. The lack of rapid and robust methods for verifying product authenticity poses a significant challenge to the protection of legal and consumer rights, emphasizing the need for the development of fast and reliable authentication techniques.

In this work, VIS–NIR spectra (350-2500 nm) recorded from commercial salep products available on the domestic market, including products spiked with pure authentic salep, were analyzed by principal component analysis (PCA) after standard normal variate (SNV) correction. Unsupervised PCA loading profiles showed the visible range (400–700 nm) as an appropriate marker region for the authentication, reflecting the contrasting color of off-white salep relative to the whiter diluents, and a near-infrared band near 1850–1900 nm, corresponding to the O–H stretch-plus-bend combination band of the hydroxyl-rich, high-bound-water glucomannan matrix. In addition to his, a Hotelling’s T² analysis flagged three commercial products as containing little or no genuine salep. These results show that a single, rapid, non-destructive and low-cost VIS–NIR measurement can both quantify salep content and thus expose its near-absence in cheap commercial preparations.

Speaker: Dr Kosta Najkov (Ss. Cyril and Methodius University in Skopje, Faculty of Natural Sciences and Mathematics, N. Macedonia)

18:25 Redox Chemistry of Polyphenols- Green Synthesis of Silver Nanoparticles and Electrochemical Interactions of Quercetin with Dopamine

Polyphenolic compounds exhibit diverse redox properties that determine both their ability to reduce metal ions and their interactions with biologically relevant electroactive molecules. In this study, green synthesis of silver nanoparticles using grape seeds as natural polyphenol sources and the electrochemical behavior of quercetin in the presence of dopamine were investigated. Intact grape seeds served as reducing and stabilizing agents for AgNP synthesis from aqueous AgNO₃ solutions[1]. UV–VIS spectroscopy confirmed nanoparticle formation through the characteristic localized surface plasmon resonance band at 410–430 nm, while SEM analysis revealed predominantly spherical particles with diameters of 20–50 nm. The developed protocol represents a simple, eco-friendly approach aligned with Green Chemistry principles. The electrochemical properties of quercetin were examined in phosphate buffer (pH 7) using square-wave voltammetry. Quercetin exhibited a quasi-reversible redox process at approximately +70 mV versus Ag/AgCl, with diffusion-controlled behavior at low frequencies (1–10 Hz), whereas higher frequencies resulted in decreased responses due to kinetic limitations. Dopamine displayed a reversible redox transformation at approximately +0.20 V. Simultaneous measurements revealed weak but detectable interactions between quercetin and dopamine, while preserving sufficient peak separation for their individual identification. These findings highlight the importance of polyphenol redox chemistry in sustainable nanoparticle synthesis and biologically relevant electrochemical systems.
Keywords: dopamine; grape seeds; green synthesis; polyphenols; quercetin; redox interactions; silver nanoparticles; square-wave voltammetry.
References: [1] S. Lazarova, P. Apostoloski, R. Gulaboski, Monatshefte für Chemie - Chemical Monthly. 2023, 154, 1-9.

Speaker: Sanja Lazarova (Faculty of Medical Sciences, Goce Delcev University, Stip, North Macedonia)

18:30 COMPLEXATION OF METAL CATIONS WITH THIOAMIDE CALIX[4]ARENE DERIVATIVE

Calixarenes are a class of supramolecular ligands that can be readily functionalized to give very efficient and even selective receptors for various ionic and neutral chemical species.1,2 Among them, those bearing sulfur-based functional groups form stabile complexes with low-charge-density and soft metal cations.3 In the scope of this work, binding affinity of thioamide calix[4]arene derivative towards alkali, alkaline earth, and soft metal cations in acetonitrile was investigated by spectrophotometry, NMR spectroscopy, isothermal titration calorimetry, and X-ray crystallography. The obtained results were discussed regarding the structural characteristics of the ligand, as well the size, charge density, and polarizing power of the cations.

Keywords: calixarenes, metal cations, thermodynamics
References:
1 Gutsche, C. D.; Calixarenes: An Introduction, 2nd edition, The Royal Society of Chemistry, Cambridge, 2008.
2 a) Modrušan, M.; Cindro, N.; Usenik, A.; Leko, K.; Glazer, L.; Tomaš, R.; Horvat, G.; Požar, J.; Tomišić, V. Croat. Chem. Acta, 2024, 97, 1–15; b) Požar, J.; Cvetnić, M.; Usenik, A.; Cindro, N.; Horvat, G.; Leko, K.; Modrušan, M.; Tomišić, V. Molecules 2022, 27, 470; c) Leko, K.; Usenik, A.; Cindro, N.; Modrušan, M.; Požar, J.; Horvat, G.; Stilinović, V.; Hrenar, T.; Tomišić, V. ACS Omega, 2023, 8, 43074–43087; d) Cvetnić, M.; Cindro, N.; Bregović, N.; Tomišić, V. ACS Phys. Chem Au, 2024, 4, 6, 773–786.
3 a) Delaigue, X.; Harrowfield, J. McB.; Hosseini, M. W.; De Cian, A.; Fischer, J.; Kyritsakas, N. J. Chem. Soc., Chem. Commun. 1994, 1579; b) Danil de Namor, A. F.; Pawłowski, T. S.; New J. Chem. 2011, 35, 375–384; c) Śliwa, W. J. Incl. Phenom. Macrocycl. Chem. 2005, 52, 13–37.

Speaker: Dr Katarina Leko (University of Zagreb Faculty of Science Department of Chemistry)

Friday 25 September

09:00 → 09:30 Industrial Symbiosis through Secondary Gypsum Resources for Circular Construction

Industrial Symbiosis through Secondary Gypsum Resources for Circular Construction
Diana Bajare1, Girts Bumanis1
e-mail: diana.bajare@rtu.lv

1 Riga Technical University, Faculty of Civil and Mechanical Engineering, Institute of Sustainable Building Materials and Engineering

Gypsum-containing waste is a valuable secondary resource that supports circular construction and reduces landfill disposal. Three circular gypsum streams were assessed: synthetic gypsum (SG), phosphogypsum (PG), and recycled plasterboard gypsum (RPG).
SG exhibits a considerably finer particle-size distribution than commercial gypsum (58–78% vs. ~4% below 63 μm). While this enables binder production at relatively low calcination temperatures (105–120 °C), excessive fineness may increase water demand and limit direct utilization in conventional gypsum products.1 PG consists predominantly of calcium sulfate dihydrate (D50 ≈ 74 μm; commercial gypsum ≈ 140 μm) and contains residual phosphorus compounds (P₂O₅ ≈ 0.6 wt.%), which may affect hydration kinetics and prolong setting times.² RPG exhibits the highest compositional variability due to differences in plasterboard composition and additives. Following calcination at 160–180 °C, RPG can be converted into a secondary gypsum binder, while high-temperature treatment (~700–800 °C) may provide a route to more uniform anhydrite binders.1
The suitability of SG, PG, and RPG as substitutes for natural gypsum was evaluated in commercial gypsum products with replacement levels ranging from 0 to 30 wt.%. Secondary gypsum resources were also incorporated into gypsum–cement–pozzolan (GCP) systems, achieving compressive strengths of up to 50 MPa after 28 days.2 These materials demonstrated potential for additive manufacturing applications, partly due to their favourable pore structure, as revealed by micro-computed tomography.2
The findings highlight the potential of secondary gypsum resources to contribute to circular construction by reducing reliance on virgin raw materials and promoting the valorization of industrial and construction waste streams.3,4

Keywords: secondary gypsum, synthetic gypsum, phosphogypsum, recycled plasterboard gypsum, industrial symbiosis, circular economy, sustainable construction.

References:
1. G. Bumanis, et.al, Processing of gypsum construction and demolition waste and properties of secondary gypsum binder, Recycling, 7 (2022) 30.
2. G. Sahmenko, et.al, Gypsum–cement–pozzolan composites for 3D printing: Properties and life cycle assessment, J. Compos. Sci., 8 (2024) 212.
3. G. Bumanis, et.al, Circular economy in practice: A literature review and case study of phosphogypsum use in cement, Recycling, 9 (2024) 63.
4. K. Weimann, et.al, Environmental evaluation of gypsum plasterboard recycling, Minerals, 11 (2021) 101.

Speaker: Prof. Diana Bajare (Riga Technical University)

09:30 → 10:00 Watching Nanomaterials Transform on Atomic Scale: In-Situ Environmental TEM of Redox and Phase Dynamics

In-situ environmental scanning transmission electron microscopy (e-STEM) provides a powerful platform for atomic-scale characterisation of materials under realistic and dynamic conditions. Such approaches are increasingly critical for advancing functional materials in energy applications, including nuclear and fusion systems, photovoltaics, batteries, and heterogeneous catalysis.
At York, we have developed open-cell environmental TEM/STEM methodologies, recently implemented on a double aberration-corrected JEOL NeoARM cold field-emission gun instrument (ARTEMIS). This system builds on our earlier environmental TEM developments and enables a broad range of in-situ experiments, combining variable accelerating voltage, controlled gas and vapour environments, 4D-STEM diffraction, and atomic-resolution EDX and EELS spectroscopy.
In this work, we highlight the capabilities of the ARTEMIS platform through three representative case studies. First, we examine redox processes in Ni/NiO and Fe nanoparticles under H₂, H₂O vapour, and O₂ environments, achieving single-atom sensitivity using HAADF-STEM under controlled temperature and gas conditions. Second, we investigate structural phase transformations in TiO₂ nanoparticles, including the formation of Magnéli phases, driven by electron-beam irradiation and influenced by environmental and thermal parameters. Third, we demonstrate in-situ, electron-beam-directed three-dimensional atomic restructuring of NiO nanoflowers via precursor-mediated β-hydroxide and nitrate–hydroxide intermediates.
These studies illustrate the unique capability of in-situ e-STEM to directly resolve dynamic processes at the atomic scale, providing insights into reaction pathways and structural evolution that are essential for the rational design of next-generation functional nanomaterials.

Speaker: Vlado Lazarov (University of York)

10:30 → 11:00 From Natural Polymers to Functional Adsorbents for Water and Wastewater Treatment

Increasing degradation of the global aquatic environment has intensified the search for new, low-cost adsorbents with reduced toxicity, particularly those derived from natural and renewable sources. In response to these challenges, growing attention has been directed toward sustainable and biodegradable materials such as lignin, cellulose, and starch. These biopolymers, due to their abundance, low environmental impact, and favorable physicochemical properties, represent promising alternatives to conventional synthetic polymers, especially those derived from petrochemical sources. Their use aligns with the principles of green chemistry and circular economy, which aim to minimize waste generation and promote the use of renewable resources.
Numerous studies have demonstrated that polymers of natural origin can effectively replace synthetic counterparts while maintaining high adsorption efficiency. Moreover, the incorporation of such biopolymers into advanced material systems allows for the design of functional adsorbents with tunable properties, improved selectivity, and enhanced environmental compatibility.
This study presents a comprehensive approach to the development of eco-friendly adsorbents based on natural and renewable biopolymers, including lignin, cellulose, and starch, incorporated into functional polymer matrices. These materials were synthesized using monomers such as ethylene glycol dimethacrylate (EGDMA), triethylene glycol dimethacrylate (TEGDMA), vinyl acetate (VA), and triethoxyvinyl silane (TEVSi), enabling the formation of crosslinked, porous microspheres with tailored surface properties.
The obtained materials were thoroughly characterized and demonstrated effective removal of toxic dyes, such as C.I. Basic Yellow 2, C.I. Basic Blue 3, C.I. Basic Red 46, and C.I. Acid Violet 1. The adsorption behavior was found to be influenced by factors including lignin content, the presence of surfactants and electrolyte, confirming the strong potential of these materials as sustainable and cost-effective adsorbents for wastewater treatment applications.

Speaker: Monika Wawrzkiewicz (Maria Curie-Sklodowska University in Lublin, Poland)

11:00 → 11:30 Influence of Moisture on the Molecular Structures of Pyrazole-Based Cadmium Halide Complexes

Due to the aromatic nature of the pyrazole ring, pyrazole derivatives are potentially applicable as luminescent materials, sensors, and functional materials. The flexible coordination behavior of Cd(II), combined with the tunable electronic properties of pyrazole-based ligands, enables the formation of different structures with attractive photophysical characteristics. In this work, a series of cadmium halide complexes (CdX₂, X = Cl, Br, I) with ethyl 5-amino-1-methyl-1H-pyrazole-4-carboxylate was synthesized under different reaction conditions and characterized by structural, spectroscopic, and thermal methods. Structural investigations revealed that the presence of water significantly affects the coordination environment of the Cd(II) centers and the resulting crystal structures, leading to the formation of different compounds from the same precursors. These moisture-induced differences demonstrate the sensitivity of the complexes to environmental conditions and highlight the role of water in the formation of the coordination compounds. Except for CdI2, synthesis with other halides yielded the coordination polymers, promising for light-harvesting applications. These findings contribute to a better understanding of the relationship between synthesis conditions, solid-state structure, and material properties, which is essential for the rational design of coordination compounds with tailored functionalities and potential applications in optical and advanced functional materials.
Acknowledgement: The authors gratefully acknowledge the financial support of the Ministry of Science, Technological Development and Innovation of the Republic of Serbia (Grants No. 451-03-33/2026-03/ 200125 & 451-03-34/2026-03/ 200125).‬‬‬

Keywords: pyrazole derivative, cadmium complex, moisture, structure.

Speaker: Berta Barta Holló (University of Novi Sad Faculty of Sciences)

11:40 → 13:40 Parrallel E-poster Presentations (2B): Biljana Hall

11:40 Antibiotic Residues in Agricultural Soils

Antibiotics are indispensable in the treatment of infectious diseases in humans and are extensively applied in veterinary practice, animal husbandry, and aquaculture worldwide. Their growing discharge into aquatic and terrestrial ecosystems, however, raises concerns about adverse effects on native microbial communities. Within this context, agricultural soils remain an insufficiently explored pathway of environmental contamination, as residues originating from partially unmetabolised pharmaceuticals can be introduced into cropland through manure, digestate, treated sewage sludge, and reclaimed irrigation water.
In the Hungary-Serbia border region, where organic fertilizers and irrigation are important inputs to crop production, the contribution of these practices to antibiotic loads in soils, their potential uptake by plants and the associated risk of antimicrobial resistance (AMR) development has not been systematically assessed. This work, developed in the framework of cross-border cooperation established through the Interreg IPA Hungary-Serbia (HU-SRB) Programme and aligned with the proposed PLANTSAFER project, aims to generate a shared evidence-base on antibiotic occurrence in agricultural soils and to support risk-informed management of the soil-plant continuum within a One Health approach. An advanced LC-HRMS-based workflow designed for multi-residue determination, combining optimized extraction and clean-up of soil samples with targeted and suspect screening analysis, is used for determination of selected antibiotics in soil samples from the Vojvodina Province (Serbia). The results are compared with relevant literature data. This preliminary work provides a basis for the next project phase, which will integrate chemical, microbiological and molecular biological tools to assess antibiotic transfer, AMR risk, pollution reduction options, and biodiversity protection measures in the HU-SRB border area.

Speaker: Prof. Nataša Đurišić-Mladenović (University of Novi Sad, Faculty of Technology Novi Sad)

11:45 MONITORING THE ORGANIC MATTER CONTENT IN BOTTOM SEDIMENT SEGMENTS ALONG THE STRUGA SHORELINE OF LAKE OHRID

This study examines the organic matter content of bottom sediments collected from five selected locations along the Struga shoreline of Lake Ohrid, with the objective of identifying its potential sources. Organic matter in lake sediments is an important indicator of ecosystem productivity, sedimentary processes, and anthropogenic influence1,2. Each sampling location comprised five sampling points situated at distances of 5, 10, 15, 20, and 25 m from the shoreline. Total organic matter content was determined using the loss-on-ignition (LOI) method through gravimetric analysis, with sediment samples combusted at 600°C for 1 hour. In parallel, sediment moisture content was measured to assess the primary medium associated with organic matter accumulation. The results revealed substantial spatial variability in organic matter content, ranging from 5.54% to 16.17% across all samples. Comparison of moisture and organic matter data suggests that organic matter is predominantly associated with the water-rich fraction of the sediment, while a smaller proportion is adsorbed onto mineral particles. Elevated organic matter concentrations were observed at sites exposed to pronounced anthropogenic influence or to a combination of natural and anthropogenic factors.
The highest values were recorded near the mouth of the Sateska River, indicating that the river is a significant source of organic matter entering Lake Ohrid. This pattern is most likely related to the transport of organic pollutants and other anthropogenic inputs originating from the Sateska River catchment.

Keywords: Organic matter, lake sediment, Lake Ohrid, anthropogenic impact

References:

1. Robert G. Wetzel (2001). Limnology: Lake and River Ecosystems (3rd ed.). Academic Press.
2. Philip A. Meyers & Ryo Ishiwatari (1993). Lacustrine organic geochemistry—an overview of indicators of organic matter sources and diagenesis in lake sediments. Organic Geochemistry, 20(7), 867–900.

Speaker: Elena Arsoska

СХТМ 2026 - MONITORING THE ORGANIC MATTER CONTENT IN BOTTOM SEDIMENT SEGMENTS ALONG THE STRUGA SHORELINE OF LAKE OHRID.pptx

11:50 EVALUATING HEAT TRANSFER DISTRIBUTION IN SOIL PROFILES

The present study investigates heat transfer and heat distribution within soil profiles under controlled non-adiabatic experimental conditions, with particular emphasis on the effects of soil moisture content, porosity, mineral composition, and compaction on soil thermal behavior. The water content in soil plays a dominant role in heat transfer because of its high specific heat capacity and the phase changes that occur during heating. This effect becomes more pronounced with increasing moisture content, particularly at 15%. Experimental measurements were performed on particularly different soil samples collected from two locations, with a constant porosity of 50% and varying moisture contents of 0.2% (dry soil), 10%, and 15%.
To eliminate the influence of heat loss associated with non-adiabatic conditions, a reference water system was employed under identical experimental conditions. Analysis of heat distribution showed that thermal energy was partitioned among the mineral, water, and air phases of the soil. The specific heat capacities of the dominant mineral constituents—quartz, calcite, albite, muscovite, clinochlore, and gypsum—were determined and evaluated in relation to the overall thermal response of the soil. The results demonstrate that heat transfer in soils is controlled by complex interactions among moisture content, water phase transitions, mineralogical composition, soil structure, porosity, and bulk density. A comprehensive understanding of these mechanisms is essential for improving soil temperature modelling, evaluating its thermal potential, and supporting agricultural and environmental applications involving heat transport through the soil systems.

Keywords: soil heat transfer, thermal conductivity, moisture, porosity, mineral composition, phase transitions.

Speaker: Elena Arsoska

СХТМ 2026 - EVALUATING HEAT TRANSFER DISTRIBUTION IN SOIL PROFILES.pptx

11:55 DETERMINATION OF PHYSICO-CHEMICAL PARAMETERS AND SOME HEAVY METALS IN SURFACE WATERS IN THE MIRUSHA RIVER

In general, river water pollution in Kosovo is a real concern for the environment and human health. This research aims to assess the water quality of the Mirusha River along its course. Eight sampling points were analyzed. Physico-chemical parameters and some of the heavy metals that are primary indicators of water pollution were determined. The levels of heavy metals (Zn, Cu, Fe and Mn) were analyzed using the atomic absorption spectroscopy (AAS) method with oven and flame. Statistical analysis was applied to process the experimental data. Water temperature, electrical conductivity, pH, total suspended matter, total soluble matter, detergents, dissolved oxygen, nitrates, sulfates and chlorides are within the permitted limits according to the EU. COD, nitrites and BOD in some sampling points have shown higher values that exceed the EU recommendations. This may be more related to anthropogenic pollution. The total hardness, calcium and alkalinity in the waters of the Mirusha River stream resulted lower than the recommended value, classifying the waters of the Mirusha River stream as soft waters. Cadmium and lead concentrations for some sampling points exceeded the permitted values and this mainly refers to anthropogenic pollution and the geological composition of rocks and soil. Chromium and nickel showed higher values than the recommended value according to EU Directive 98/83/EC and these high levels can be attributed to the rock formation of the soil. This research provides knowledge on possible sources of pollution, helping relevant institutions in taking effective actions to minimize this form of pollution.

Speaker: Valmire Krasniqi (The Ministry of Environment and Spatial Planning with Skat Consulting Ltd. Branch in Kosovo Integrated Water Resource Management Program (IWRM-K) str. Pashko Vasa St., ent.8, fl.5 no.5, Peyton, 10000 Pristina, Republic of Kosovo)

12:00 SILVER NANOPARTICLE THIN FILMS AS POTENTIAL ADSORBENTS FOR PASSIVE SAMPLING OF HYDROPHOBIC ORGANIC POLLUTANTS IN WATER

The contamination of water resources by organic pollutants represents a significant environmental challenge worldwide. Monitoring these pollutants is essential for assessing water quality and reducing environmental risks. In this work, silver nanoparticle (Ag NP) thin films were investigated as functional substrates for the extraction of organic pollutants from aqueous samples prior to chromatographic analysis.
The Ag NP thin films were deposited on polyester substrates and glass using a cost-effective bottom-up synthesis method1, yielding nanostructured surfaces with low porosity and a high density of active sites capable of interacting with organic molecules. The structural and morphological properties of the films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM), confirming the formation of nanostructured silver domains with a high surface area.
The Ag NP thin films deposited on polyester sheets were tested as potential passive samplers for organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) by spiking them with 22 OCPs and 7 PCBs and then desorbing them by extraction with 5% diethyl ether in hexane. Recoveries from 38 to 115% were obtained for OCPs and between 88 and 120% for PCBs. Further, when exposed to spiked aqueous solutions, they showed a higher affinity for retaining aromatic organochlorine compounds than alicyclic ones.
The Ag NP thin films were then exposed to surface water for one month and Ag NP on polyester sheets were found as more stable for further tests compared to ones on glass. During this exposure period, the films captured 10 target OCPs and PCB congeners. In addition, 51 other organic contaminants were detected: 14 PAHs, 13 fragrance-related compounds, 9 industrial and plasticizer-related compounds, 5 pyrethroids, 4 antioxidant additives, and two additional compounds (a UV filter and an OCP). 86% contained an aromatic ring, consistent with the higher retention of aromatic compounds observed in the laboratory affinity tests. The reusability of the Ag NP-coated polyester sheets was also evaluated over three exposure–desorption cycles, with no statistically significant differences among the cycles.
Results suggest that Ag NP thin films on polyester sheets show potential for application as passive samplers for monitoring aromatic organic compounds in water media.

Speaker: Ivona Sofronievska (Ss. Cyril and Methodius University, Faculty of Natural Sciences and Mathematics, Institute of Chemistry)

12:05 Wood Wastewater Purification with Activated Carbon and Purity Analysis via GC-MS and Capillary Electrophoresis with direct UV Detection

Acetic acid is an organic acid widely utilized across food, chemical, pharmaceutical, textile, packaging and other industries. Due to high global demand, recovering and valorizing it from industrial waste streams presents an economically attractive alternative.1 Various methods exist for recovering acetic acid, including liquid-liquid extraction, reactive extraction, membrane extraction, and reactive distillation.2,3 However, to implement methods like reactive extraction, it is best to use activated carbon to clear the sample of any interfering compounds.4
The objective of the present study is to optimize the parameters of activated carbon filtration: carbon type, carbon amount, sonication time, filtration amount. Filtration efficiency was evaluated using Gas Chromatography-Mass Spectrometry (GC-MS) and capillary electrophoresis-UV. The primary target for filtration was furfural. The concentration of acetic acid was monitored using both analytical techniques to ensure if there were any losses. Preliminary results indicate that while activated carbon filtration is highly effective, the process requires further optimization. Visually, the treatment successfully transforms dark brown wastewater into a clear effluent. To minimize product loss and maximize efficiency, future work will focus on utilizing activated carbons specifically tailored for wood wastewater treatment.

Keywords: activated carbon, wood wastewater, GC-MS, CE-UV

References

1. G. Deshmukh and H. Manyar, "Production Pathways of Acetic Acid and Its Versatile Applications in the Food Industry," Biotechnical Applications of Biomass, 2019. DOI: 10.5772/intechopen.92289
2. G. Bhoj, S. Patil, S. Gadale and S. Gadekar-Shinde, "Reactive Extraction of Acetic Acid from Aqueous Sodium Acetate Waste," Nature Environment and Pollution Technology, vol. 24, no. 4, 2025. DOI: 10.46488/NEPT.2025.v24i04.B4304
3. A. Singh, A. Tiwari, M. Mahajani, Sanjay and R. D. Gudi, "Recovery of Acetic Acid from Aqueous Solutions by Reactive Distillation," Industrial & Engineering Chemistry Research, vol. 45, no. 6, pp. 2017-2025, 2006. DOI: 10.1021/ie0505514
4. G. Yang, M. S. Jahan, L. Ahsan, L. Zheng and Y. Ni, "Recovery of acetic acid from pre-hydrolysis liquor of hardwood kraft-based dissolving pulp production process by reactive extraction with triisooctylamine," Bioresource Technology, vol. 138, pp. 253-258, 2013. DOI: 10.1016/j.biortech.2013.03.164

Speaker: Violetta Umerenkova (Tallinn University of Technology, Tallinn, Estonia)

12:10 Profiling of the Liquid Phase From Hydrothermal Carbonization of Waste Wood: Antioxidant Properties and PAH Content

Hydrothermal carbonization (HTC) is increasingly recognized as a promising thermochemical process for the valorization of biowaste, enabling the conversion of lignocellulosic residues into a carbon-rich solid hydrochar and an aqueous liquid phase containing various organic compounds. In this study, HTC of waste wood was investigated, with particular emphasis on the chemical composition, antioxidant properties, and safety-related aspects of the resulting liquid phase. The process was performed at temperatures of 200 and 250 °C, liquid-to-solid ratios of 5:1 and 15:1, and residence times ranging from 30 to 165 min, under pressures between 192 and 584 psi.
Four selected liquid-phase samples obtained under different HTC conditions were characterized. The samples were strongly acidic, with pH values ranging from 2.7 to 3.1, and contained total organic carbon (TOC) concentrations between 211 and 550 mg C/L. Phenol concentrations varied from 16.9 to 75.8 mM, while total polyphenol content ranged from 0.352 to 0.588 g GAE/g. Pronounced antioxidant activity was observed in all samples, with DPPH radical scavenging values between 70.8 and 87.0%, indicating the presence of redox-active organic compounds formed during HTC.
To evaluate potential safety concerns, the liquid phase was analyzed for the 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) using gas chromatography–mass spectrometry (GC–MS) after liquid–liquid extraction.
The presence of PAHs was confirmed, suggesting that aromatic and potentially hazardous compounds may be generated or transferred into the aqueous phase during the HTC process.
Overall, the results indicate that the liquid phase obtained from HTC of waste wood is a chemically active by-product with both valorization potential and environmental relevance. Although its antioxidant activity suggests the presence of potentially valuable organic compounds, its acidic character, organic load, and confirmed PAH content emphasize the need for careful assessment and appropriate treatment before reuse or discharge.

Speaker: Maja Buljovcic (Faculty of Technology Novi Sad)

12:15 ROLE OF SURFACE MODIFICATION COAL IN ENHANCING THE PROPERTIES OF REVERSE OSMOSIS MEMBRANES

High-performance reverse osmosis membranes are expected to simultaneously exhibit high solute rejection, elevated water permeability, excellent chemical stability, and strong resistance to compaction, particularly in aqueous separation applications.1 For several decades, aryl diazonium salts have been employed as reagents to modify a wide range of substrates, including carbons, metals, metal oxides (e.g., ZnO, Al₂O₃), nanomaterials, semiconductors, and polymer surfaces, with aryl moieties.2 The resulting grafted layers have diverse applications, including surface modification of membranes.3 The methods used for the modification of material surfaces involve both physical and chemical processes. Membrane surface properties - including charge density, hydrophobicity/hydrophilicity, and fouling resistance - can be tuned by grafting organic molecules. Such modifications enhance separation performance while maintaining mechanical and chemical robustness.
This paper examines the role of aryldiazonium salt concentration in an aqueous acid medium in the chemical grafting of aryl moieties onto the coal surface, which is subsequently used for reverse osmosis (RO) membrane preparation. Coal particles' surfaces were modified by chemical reduction of 4-nitrobenzene diazonium salt of different concentrations at aqueous acid solution (hypophosphoric and sulfuric). The ATR-FTIR spectra show that the nitrophenyl groups were strongly bonded on the surface of coal particles. The introduction of aryl groups onto the coal surface and thus in RO membranes alters their characteristics, as shown by reverse osmosis parameters as well as SEM images. The resulting membranes showed the best results with coal particles modified with a middle concentration of aryldiazonium salt in aqueous medium with hypophosphoric acid. At an acceptable reverse osmosis salt rejection level (94.55 %) of NaCl-H2O of concentration of 0.4 g/dm3 as a referent system at 1.76 MPa, the flux was 42.6 L/hm2.

Speaker: Dr Gentiana Hasani-Bekteshi (University of Prishtina)

12:20 Chromatographic performance evaluation of a bio-renewable solvent using design of experiments

Green chemistry principles are increasingly applied in chromatographic analysis to reduce the environmental impact associated with high solvent consumption and hazardous waste generation. In this context, the use of bio renewable solvents (BRS) in chromatographic methods offers a sustainable alternative to conventional organic eluents (ex. acetonitrile, methanol), enabling efficient separations while improving safety and reducing ecological footprint.1
This study explored the chromatographic behavior of a selected BRS, belonging to the group of lignocellulose derivatives, whose performance remains poorly characterized, using a Central Composite Face (CCF) 2² experimental design. The effects of two critical factors (the percentage (v/v) of BRS in the mobile phase and the column temperature) on mobile phase viscosity, retention factor (k′), and column backpressure were evaluated through a set of 12 experiments generated by the design of experiments (DoE) software MODDE®, employing a 1% (v/v) toluene solution as a retention marker on a LiChrospher® 100 RP 18 column (125 × 4 mm, 5 µm).
The multiple linear regression model demonstrated excellent fit (R² ≈ 0.99 - 1.00) and predictive reliability (Q² ≈ 0.997) for all responses. Within the studied domain, viscosity ranged from 1.37 to 2.17 mPa·s, column pressure from 84.9 to 160.5 bar, and retention factor from 1.5 to 30.4. Optimal chromatographic performance was achieved at an intermediate percentage of BRS (≈45-55%) in the mobile phase and moderate temperature (≈38-42 °C), where viscosity (≈1.5 mPa·s), retention factor (≈4.7), and pressure (≈122 bar) were simultaneously balanced.
These findings provide a rational basis for selecting sustainable chromatographic conditions, supporting safer and more environmentally responsible analytical practices.

Keywords: bio-renewable solvent, green chemistry, liquid chromatography, CCF experimental design

References:
1. Shaaban, H. New Insights into Liquid Chromatography for More Eco-Friendly Analysis of Pharmaceuticals. Anal. Bioanal. Chem. 2016, 408, 6925–6938. https://doi.org/10.1007/s00216-016-9726-2

Speaker: Aneta Lazarevska Kamcheva (Alkaloid AD Skopje)

Chromatographic performance evaluation of a bio-renawable solvent using DoE.pptx

12:25 From Monitoring to Prioritisation: The EnviLife Framework for Emerging Contaminants

The growing presence of contaminants of emerging concern (CECs) in aquatic environments poses a significant challenge for environmental protection and sustainable agriculture. This issue is particularly critical in intensively agricultural regions where surface water is widely used for irrigation, such as the Danube-Tisa-Danube (DTD) hydro-system in Vojvodina, northern Serbia. Despite increasing awareness and regulatory efforts at the European level, significant knowledge gaps remain regarding the occurrence, distribution, and prioritisation of CECs in complex agro-environmental systems.
Within the EnviLife project, a multidisciplinary framework has been developed to detect and prioritise CECs in surface water and arable soil. A central component of this framework is the application of wide-scope high-resolution mass spectrometry (HRMS), integrating suspect screening with target analysis to achieve comprehensive chemical characterisation and reliable quantification of prioritised contaminants in environmental samples.
This analytical approach is further supported by an advanced data processing workflow, a prioritisation strategy, and the development of predictive models based on machine learning and environmental datasets. The resulting data enable the formulation of a region-specific watch list of CECs, supporting the monitoring of prioritised compounds and improving understanding of potential contaminant transfer pathways between water and soil.
The proposed framework supports the design of future monitoring strategies and advances understanding of CEC occurrence in the DTD hydro-system. While developed for a specific hydro-system, the approach and findings are broadly applicable to other agro-environmental systems facing similar contamination pressures.

Speaker: Jelena Zivancev (University of Novi Sad, Faculty of Technology Novi Sad, Serbia)

12:30 Short discussion

12:40 OPTIMIZATION OF DEEP EUTECTIC SOLVENT-BASED EXTRACTION OF PERSISTENT ORGANIC POLLUTANTS FROM HUMAN HAIR

Human hair is increasingly used as a non-invasive biomonitoring matrix for persistent organic pollutants (POPs), providing information on long-term exposure to environmental contaminants. Determination of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in human hair is important due to their persistence, bioaccumulation potential, and adverse effects on human health. However, efficient extraction and clean-up procedures remain challenging due to the complexity of the hair matrix and the low concentrations of target analytes.
In this study, extraction and clean-up conditions for the determination of OCPs and PCBs in human hair were optimized. Method development and optimization were performed using human hair samples previously exposed to elevated concentrations of pesticides.
Ten conventional organic solvents and mixtures, together with one deep eutectic solvent (DES) were tested. Hexane:dichloromethane (4:1, V/V) and DES composed of menthol and levulinic acid (1:1 molar ratio) provided the highest extraction efficiency. To align with the principles of green chemistry, DES was selected for further optimization steps.
Different extraction techniques were subsequently compared, including thermal incubation, mechanical agitation, Soxhlet extraction and reflux extraction. The combination of thermal incubation followed by mechanical agitation resulted in the highest extraction of target analytes. Extraction parameters were optimized using response surface methodology (RSM) based on a Box–Behnken design. The effects of solvent volume (3, 5 and 10 mL), incubation temperature (30, 40 and 50 °C) and incubation time (30, 60, and 90 min), were investigated, followed by an additional mixing step. The optimal extraction conditions were established as 10 mL of DES, incubation at 40 °C for 45 min, followed by 45 min of mechanical agitation. For sample clean-up, nine different solid-phase extraction sorbents were evaluated. Deactivated alumina provided the best overall clean-up performance.
The optimized method enables efficient determination of organochlorine pesticides in human hair while reducing the use of conventional organic solvents, making it a promising approach for future environmental and human biomonitoring studies.

Keywords: organochlorine pesticides, human hair, deep eutectic solvents, biomonitoring

Acknowledgement: The authors gratefully acknowledge the financial support by the Macedonian Ecological Society for the project titled “Assessment of human exposure to persistent organic pollutants in Skopje using human hair biomonitoring”.

Speaker: Sandra Shterjova (Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University in Skopje, North Macedonia)

12:45 Cost-Effective Silicone Foam Samplers for Monitoring Organic Compounds in Air

Air pollution by diverse organic compounds poses environmental and human health concerns, while personal exposure monitoring remains challenging. Conventional air sampling often relies on sorbents such as polyurethane foam (PUF) and synthetic polymers, which may have limitations related to cost, stability, and chemical interferences. Silicone-based materials offer a promising alternative due to their affinity for a broad range of organic compounds.
In this study, silicone (polydimethylsiloxane, PDMS) foam was prepared and evaluated as a low-cost sorbent for active and personal passive air sampling. PDMS foam was prepared from a two-component silicone elastomer system (elastomer/curing agent, 10:1) using sieved NaCl to generate the porous structure followed by curing and salt removal, and characterized by infrared spectroscopy. Extraction with ethyl acetate was optimized using ultrasound-assisted and Soxhlet procedures, yielding recoveries of 70–123% and 69–129%, respectively.
The prepared PDMS foam was successfully applied for active air sampling (4 L/min, 24 h) enabling the detection of 20 organochlorine compounds at concentrations of 0.91–531 pg/m3 air. In addition, to test its suitability as a personal passive air sampler, seven PDMS samplers were worn by participants in Skopje for 9 days and analyzed by GC-ECD and GC-MS following ultrasound-assisted extraction. 14 organochlorine compounds were identified by GC-ECD, including chlorobenzenes (7), HCH isomers (3), other organochlorine pesticides (2), and PCBs (2). 1,3,5-Trichlorobenzene, tetrachlorobenzene isomers, penta¬chlo¬robenzene, and PCB 180 were most frequently detected with normalized concentrations from 1.4 to 41.1 ng/g sampler. In addition, 13 of 16 target polycyclic aromatic hydrocarbons (PAHs) were detected, individual amounts ranging from 0.16 to 29.72 ng/g sampler. Fluorene, phenanthrene, chrysene, and benzo[k]fluoranthene showed the highest concentrations, reflecting combustion-related and urban sources, including traffic and tobacco smoke, as well as indoor activities such as cooking. Additionally, a diverse range of 45 other organic compounds were detected, including aliphatic and aromatic hydrocarbons, esters, oxygenated compounds, terpenes, fragrances, phthalates/plasticizers, and UV filters. Overall, these findings demonstrate the potential of PDMS foam for both active and personal passive air sampling of diverse organic compounds.

Keywords: silicone foam, air pollution, air sampling, passive sampler, GC-ECD, GC-MS

Speakers: Aleksandra Gjerasimovska (Faculty of natural sciences and mathematics, institute of chemistry), Veronika Gijovska

12:50 MONITORING OF THE QUALITY OF AIR IN QUARRY

Measuring points of air pollution pollution by stones are chosen in locations where there is the greatest risk of exceeding the limit values. The places proposed for monitoring are the open-pit mine and the zone of the nearest rural housing facilities. The measuring point should be sufficiently large, easily accessible and equipped so that the measurement can be carried out in the prescribed manner and without danger to the measuring operator.
The measurement procedure included the following operations: Location survey; Installation of sedimentators; GPS location measurement; Sampling in a given period of time; Transport of samples to the laboratory; - Preparation of chemical analyses
The measuring device used for air quality testing in the quarry "Draževići" is an analytical balance METLLER TOLEDO measuring range from 0 to 220 g. The values of total sedimentary substances (mg/m ²/day) were measured in the period from 17.11.2020 to 17.12.2020, 21.06.2022 - 21.07.2022 and 11.07.-10.08.2024. 3 different places near the quarry.
In the observed period in the quarry "Draževići" the maximum permissible concentrations (MDK) for total sedimentary substances were not exceeded. The introduction of automatic water spraying systems (sprinklers) on conveyors and crushers significantly reduces the concentration of dust in the air. The use of binders (chemical agents) that stabilize the soil surface and prevent dust from rising is also one of the methods that is increasingly used in modern quarries.

Speaker: Snežana Aksentijević (Western Serbia Academy of Applied Studies, Užice)

12:55 ASSESSMENT OF AIR POLLUTION USING MOSSES AS BIOINDICATORS IN SELECTED LOCALITIES ALONG THE PRISHTINA–MITROVICA AXIS

Air pollution is a real threat to the environment and human health. This research aims to assess air pollution with heavy metals in several locations on the Prishtina-Mitrovicë axis through atmospheric deposition using mosses as biomonitors. Mosses were used as biomonitors because they obtain nutrients mainly from atmospheric deposition. Moss samples (Pseudosclerpodium purum and Hypnum cupressiforme) were collected in accordance with the LRTAP, ICP-Vegetation convention. The levels of heavy metals (Pb, Cd, Zn, Cu, Ni, Cr, Mn, and Fe) were analyzed using the furnace and flame atomic absorption spectroscopy (AAS) method. Statistical analysis was applied to process the experimental data. The sampling points with high concentrations of the analyzed metals are: for cadmium, sampling point M5 (1.30 mg/kg), lead M11 (12.45 mg/kg), copper M5 (8.42 mg/kg), chromium M5 (4.49 mg/kg), manganese M11 (285.27 mg/kg), nickel M5 (9.18 mg/kg), iron M5 (3131.89 mg/kg) and zinc M6 51.02 mg/kg). The high level of these metals can be attributed to anthropogenic pollution (impact of the Kosovo A and Kosovo B Power Plants, the Trepça metallurgical complex, high traffic in these areas, waste dumps, quarries, etc.) and the impact of the geological composition of the soil. This research provides knowledge on potential sources of metal pollution in contaminated areas, contributing to the advancement of future research and assisting relevant institutions in taking effective actions to minimize this form of pollution.

Speaker: Albert Maxhuni (Department of Chemistry, Faculty of Natural and Mathematical Science, University of Prishtina)

13:00 SUSTAINABLE USE OF PESTICIDES FOR THE PURPOSE OF ENVIRONMENTAL PROTECTION AND EMPLOYEE SAFETY

Chemical agents used for pest control - known as pesticides, pose a significant risk to human health and the environment if they are not used in accordance with prescribed safety measures. The potential danger associated with pesticide use is increasing due to their widespread application in agriculture, forestry, animal husbandry, municipal activities, and even in the production of chemical weapons.
Improper handling during the production, transportation, distribution, use, and degradation of pesticides can have serious adverse effects on both humans and the environment, either directly or indirectly. In order to respond promptly and effectively to issues related to pesticide use, intensive and comprehensive research must be conducted on their beneficial and harmful mechanisms of action, toxicity and the monitoring of pesticide exposure.
This paper pays special attention to risk assessment, measures for controlling exposure to pesticides, physical and chemical protection during pesticide use, as well as the potential acute and chronic effects of exposure. The aim is to raise awareness of the need for an integrated approach to protection, encompassing technical, organizational, and health-related measures, in order to preserve human health and protect the environment. The paper also defines measures for preventing, reducing, and eliminating harmful environmental impacts, as well as reducing health risks for individuals who come into contacat with pesticides.

Speaker: Dr Ljiljana Trumbulović (Western Serbia Academy of Applied Studies, Užice)

13:05 Multifunctional Cotton Textiles Modified with La-Doped TiO2: Self-Cleaning and Antibacterial Performance

Lanthanum-doped titanium dioxide nanopowder were successfully synthesized via sol-gel technology and deposited onto cotton textile substrates to obtain multifunctional materials. Two La-doped compositions containing 2 and 5 mol% were investigated to evaluate the influence of dopant concentration on the structural, morphological, optical, and functional properties of the coated textiles.
The prepared materials were comprehensively characterized using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), and UV-Vis spectroscopy. The analyses confirmed the successful incorporation of La into the TiO₂ structure and the uniform deposition of the photocatalyst onto the cotton fibers while preserving the textile morphology.
The photocatalytic self-cleaning performance of the coated textiles was evaluated through the degradation of Methylene blue and Malachite green dyes. Both La-doped samples demonstrated good discoloration efficiency. Furthermore, the antibacterial properties of the functionalized textiles were assessed against Escherichia coli. A pronounced inhibition of bacterial growth was observed for all modified samples, with the antibacterial effectiveness increasing with the lanthanum content.
The obtained results demonstrate that La-doped TiO2-coated cotton textiles exhibit promising self-cleaning and antibacterial properties, making them attractive candidates for advanced functional textile applications in healthcare, environmental remediation, and protective materials.

Speaker: Stefani Petrova (Institute of General and Inorganic Chemistry - Bulgarian Academy of Sciences)

28-SCTM-e-poster_Stefani_Petrova_.pptx

13:10 Using natural extracts for imparting color and antioxidant activity to cotton, cellulose acetate, and polyamide fabrics

Potentilla erecta L., Galium verum L., and Melilotus officinalis L. extracts were prepared using ultrasound-assisted extraction under the following conditions: 70% (v/v) ethanol, 30 min, 60 °C, with a liquid-to-solid ratio of 40 mL/g. After the dilution, the UV-Vis spectra of the prepared extracts were recorded, and their antioxidant activity was determined using the ABTS test. The obtained results revealed that all extracts exhibited antioxidant activities exceeding 98%. Such characterized diluted extracts were further employed for the functionalization and/or dyeing of cotton, cellulose acetate, and polyamide fabrics. The antioxidant activities of cotton, cellulose acetate, and polyamide fabrics functionalized with Potentilla erecta L. extract were found to be 90.19%, 95.78%, and 99.40%, respectively. Cotton, cellulose acetate, and polyamide fabrics functionalized with Galium verum L. extract displayed antioxidant activities of 52.56%, 79.71%, and 99.25%, respectively. Corresponding results for antioxidant activity of fabrics functionalized with Melilotus officinalis L. extract were 77.60%, 88.16%, and 100%, respectively. Among examined extracts, Potentilla erecta L. has an affinity for dyeing fabrics, therefore, their color coordinates were determined. Colorimetric measurements pointed out that functionalized cellulose acetate manifests a lighter and greener appearance compared to cotton and polyamide fabrics, while functionalized cotton fabric demonstrated a yellower tonality in relation to the cellulose acetate and polyamide fabrics. The release of bioactive compounds from nine functionalized fabrics was monitored in a physiological saline solution at 37 °C for 24 h. Based on the results, it can be concluded that cotton fabric functionalized with Potentilla erecta L. extract has the highest release of bioactive compounds, making it suitable for producing high-value-added medical textiles with protective functions such as wound dressing. Additionally, all other fabrics possessing excellent antioxidant activities (>90%) can also be considered for use in disposable medical textiles.

Speaker: Aleksandra Ivanovska (University of Belgrade, Innovation Center of the Faculty of Technology and Metallurgy)

13:15 EFFECTS OF SALT, POLYELECTROLYTE CONCENTRATION, AND pH ON THE FLAME-RETARDANT AND MECHANICAL PROPERTIES OF COATED NYLON–COTTON FABRIC

Blended nylon–cotton (NYCO) fabric combines the comfort of cotton with the strength of nylon, but its flammability limits its use in protective clothing. In this study, a sustainable, water-based coating composed of egg white proteins (EWP), pectin (P), and guanidine phosphate (GP), a phosphorus- and nitrogen-containing salt, was applied to NYCO fabric through a two-step process. The effects of salt addition, polyelectrolyte concentration, and pH on coating deposition, flame retardancy, and mechanical properties were investigated.

The EWP/P coating without GP produced only 1.8% weight gain and did not prevent complete burning. As a salt, GP induced charge screening along the pectin macromolecules, reducing electrostatic repulsion and increasing coating deposition. It also acted as an acid source and blowing agent within the intumescent system. This behavior agrees with the effects of ionic strength, pH, and charge density on weak-polyelectrolyte deposition.¹ Increasing the EWP, P, or GP concentration improved flame retardancy. The 4% EWP/(1% P–20% GP) formulation was subsequently deposited at pH 2, 3, and 4 to evaluate the influence of pH. Although all three coatings self-extinguished, pH 3 provided the best balance between flame retardancy and mechanical performance, producing 14.8% weight gain and the lowest char length of 127 mm. At pH 2, deposition was accompanied by reduced tensile strength due to cellulose hydrolysis, whereas pH 4 preserved tensile strength but resulted in lower deposition and a longer char length. The pH 3 treatment retained a tensile strength of 1333.5 N, comparable to 1345.5 N for uncoated NYCO, while the coating slightly increased stiffness and reduced elongation and air permeability.² These findings show that controlling GP addition, polyelectrolyte concentration, and pH enables effective flame retardancy while preserving NYCO mechanical performance.

Keywords: nylon–cotton fabric, flame retardancy, polyelectrolyte complex, pH

References
1. Shiratori, S. S.; Rubner, M. F. pH-Dependent Thickness Behavior of Sequentially Adsorbed Layers of Weak Polyelectrolytes. Macromolecules 2000, 33, 4213–4219. DOI: 10.1021/ma991645q.
2. Petkovska, J.; Radoičić, M.; Marković, D.; Rodriguez-Melendez, D.; Smith, D. L.; Iverson, E. T.; Dimova, V.; Radetić, M.; Grunlan, J. C.; Jordanov, I. Sustainable Two-Step Polyelectrolyte Complex for Flame Retardant

Speaker: Jovana Petkovska (Faculty of Technology and Metallurgy, Ss. Cyril and Methodius University in Skopje, North Macedonia)

SCTM_e-poster_Jovana_Petkovska.pptx

13:20 LACCASE-CATALYZED OLIGOMERIZATION OF ESCULIN FOR in situ DYEING AND FUNCTIONALIZATION OF WOOL FABRIC

In pursuit of sustainable and environmentally friendly green dyeing processes, the use of laccases and natural polyphenolic compounds has emerged as a suitable alternative to the established synthetic dyeing protocols. Laccases are considered to be eco-friendly enzymes due to their use of molecular oxygen and production of water as the only by-product. The application of laccases in dyeing and functionalization of textile materials is based on their ability to oxidize a broad range of substrates including naturally occurring flavonoids. This reaction can yield colored flavonoid oligomers/polymers that have potential to be applied in textile industry as colorants. Additionally, these compounds can add novel functionalities to textile materials. Esculin, a coumarin glycoside with many beneficial biological activities, is among the substrates of laccase. In this work, laccase from Trametes versicolor was applied as a catalyst in the reaction of oligomerization of esculin to its colored oligomers enabling the in situ simultaneous dyeing and functionalization of wool fabric. The antioxidant activity of the dyed wool fabric was tested before and after washing cycle. Wool fabric showed moderate ABTS radical scavenging ability (53.32%) which remained in the same range after washing (50.78%). In order to improve the bioactivity, wool fabric was modified with chitosan and functionalized under the same conditions. The ABTS radical scavenging activity of dyed and functionalized chitosan-modified wool fabric was significantly improved, reaching an inhibition rate of 96.18%, while an inhibition rate of 80.12% was retained after the washing cycle. These results indicate that the applied process can broaden the applicability of laccase in textile industry for the production of colored and functional wool fabrics.

Speaker: Ms Ana Vukoičić (Innovation Center of the Faculty of Technology and Metallurgy in Belgrade Ltd.)

13:25 A STUDY OF COOPERATIVE INQUIRY-BASED INSTRUCTION SUPPORTED BY MOLECULAR MODELS IN CARBOHYDRATE STEREOCHEMISTRY EDUCATION

Understanding stereochemistry is fundamental to the study of biomolecules, as even subtle changes in their spatial orientation can lead to significant differences in their properties and biological activity. Despite its importance, stereochemistry is one of the most conceptually challenging topics in chemistry education, highlighting the need for innovative teaching approaches that enhance visualization and promote conceptual understanding.
The aim of this research was to examine how the application of the Inquiry-Based Learning (IBL) approach, implemented through cooperative work and the use of molecular models, affects the acquisition of knowledge in carbohydrate stereochemistry among high school students. The research was conducted in two parallel groups: the experimental group participated in a teaching process based on the IBL approach, while the control group followed the traditional methodological approach. Students in the experimental group worked collaboratively and engaged in a three-phase learning cycle: exploration, concept invention, and application. During the activities, they used molecular models to visualize, construct, and analyze three-dimensional carbohydrate structures, as well as to identify and interpret different structural representations of carbohydrates.
After the implemented intervention, data on students’ attitudes and experiences were collected using a questionnaire, while acquisition of the teaching content was assessed through a knowledge test. The questionnaire results showed that students in the experimental group found the activity highly motivating and useful for understanding stereochemical concepts, noting increased engagement and improved conceptual understanding. They also expressed a preference for interactive and exploratory teaching approaches over traditional methods. Analysis of the knowledge test results indicated that students in the experimental group achieved a higher level of content acquisition than those in the control group. These findings highlight the importance of integrating different teaching approaches to enhance teaching quality and improve student achievement.

Keywords: carbohydrate stereochemistry, conceptual understanding, inquiry-based learning, molecular models.

Speaker: Aleksandra Naumoska (Institute of Chemistry, Faculty of Natural Science and Mathematics)

11:40 → 13:40 Parrallel E-poster Presentations (2C)

11:40 Almond Shell as a Sustainable Sensor Material for Real-Time Heavy Metals Monitoring

PSSE

Almond Shell as a Sustainable Sensor Material for Real-Time Heavy Metals Monitoring

Katarina Nikolić1, Milan Kragović1, Marija Stojmenović1, Miodrag Ristović1, Radmila Lišanin1, Janez Kovač2, Jelena Gulicovski1
e-mail: katarina.nikolic@vin.bg.ac.rs

1 “VINČA” Institute of Nuclear Sciences -National Institute of the Republic of Serbia, University of Belgrade, Mike Petrovića Alasa 12-14, 11351 Belgrade, Serbia
2Institute “Jožef Stefan”, Jamova cesta 39, 1000 Ljubljana, Slovenia

Clean water is a fundamental human need increasingly threatened by rapid population growth and industrial expansion. Among the most hazardous contaminants are heavy metal ions, which are non-biodegradable, highly toxic, and prone to bioaccumulation within food chains1. These challenges create an urgent need for the development of sensors capable of real-time environmental monitoring2. In this study, almond shells, collected near Belgrade, were enriched with Bi1.55Sm0.45O3 nanoparticles and thermally converted through carbonization into a carbon-nanoparticle composite. This material was employed as a sensing platform for heavy metal detection. The materials were characterized chemically and morphologically using Scanning Electron Microscopy – Energy Dispersive X-ray Spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). SEM images revealed a scaly carbon structure with uniformly embedded nanoparticles, while XPS confirmed the successful formation of carbon and incorporation of the surface modifier. The electrochemical performance of the sensor was evaluated in a conventional three-electrode system, with the synthesized material serving as the working electrode and unmodified carbon as the control. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrated enhanced electrocatalytic activity compared with unmodified carbon. The analytical performance was assessed using anodic stripping voltammetry (ASV). The novel sensor reported the limit of detection (LOD) 0.15 µgL-1 (Cd) and 0.58 µgL-1 in a linear range from 0.22 µgL-1 to 0.11 mgL-1 and from 0.41 µgL-1 to 0.21 mgL-1 for Cd and Pb, respectively. Supported by this data, the focus of future research will be on real sample applications.

Keywords: almond shells, sensors, carbon, heavy metals, water
References:
1 Raju, C. V.; Cho, C. H.; Rani, G. M.; Manju, V.; Umapathi, R.; Huh, Y. S.; Park, J.-P. Emerging Insights into the Use of Carbon-Based Nanomaterials for the Electrochemical Detection of Heavy Metal Ions. Coord. Chem. Rev. 2023, 476, 214920. https://doi.org/10.1016/j.ccr.2022.214920
2 Dai, X.; Wu, S.; Li, S. Progress on Electrochemical Sensors for the Determination of Heavy Metal Ions from Contaminated Water. J. Chin. Adv. Mater. Soc. 2018, 6 (2), 91–111. https://doi.org/10.1080/22243682.2018.1425904

Speaker: Katarina Nikolić (Institute of Nuclear Sciences "Vinča", Belgrade)

11:45 Investigation of the Hydrophobicity of Modified Glass in Glass–TEOS–HDTMS Sandwich Structures

Soda-lime-silicate (SLS) glass is widely used in industry. To render its surface hydrophobic, it is commonly modified using different silane derivatives. Among the most widely used are alkoxysilanes, which can be anchored onto the glass surface through hydrolysis, followed by condensation between the silanol groups of the silane and those on the glass surface. Among the alkoxysilanes, tetraethoxysilane (TEOS) is unique because, after complete hydrolysis, it contains no organic groups and only OH groups attached to the Si atom. This also makes TEOS an excellent glass surface modifier, since it increases the number of active silanol groups on the glass surface, thereby making it susceptible to a higher degree of modification.

In this work, we investigated how the modification of SLS glass with hexadecyltrimethoxysilane (HDTMS), and consequently its hydrophobicity, is affected when TEOS with different degrees of hydrolysis is used as the first glass layer. In this way, a sandwich structure was built in which the first layer on the glass consisted of TEOS, onto which HDTMS was chemisorbed. The analysis was performed by recording FTIR specular reflectance spectra, from which IR reflectance–absorbance spectra and two-trace two-dimensional correlation spectra were obtained. This analysis is particularly interesting because it provides information on the IR spectra of the formed ultrathin siloxane film on top of the glass substrate, both of which possess very similar chemical structures.

The morphology of the films was analyzed using Atomic Force Microscopy, while the wetting properties were determined through measurements of the water contact angle and the calculated polar and dispersive components of the surface energy using the Owens–Wendt–Rabel–Kaelble (OWRK) method.

The obtained results show that the degree of hydrolysis of TEOS strongly depends on time, pH, and the solvent used. It will be shown that drying and curing play particularly important roles in the hydrophobicity of the modified glass, which is in connection to the content of surface silanol and siloxane groups. The hydrophobicity of the glass resulting from modification with a second HDTMS layer in each case will also be discussed.
Keywords: soda-lime-silicate glass; hydrophobicity; tetraethoxysilane; hexadecyltrimethoxysilane

Acknowledgement: This work was financially supported by the Ministry of Education and Science of the Republic of North Macedonia under National Project No. 15–6171/36.

Speakers: Amin Idrizovski (Institute of Chemistry, Faculty of Natural Sciences and Mathematics Ss. Cyril and Methodius University in Skopje, Arhimedova 5, 1000 Skopje, Macedonia), Vladimir Grujovski (Institute of Chemistry, Faculty of Natural Sciences and Mathematics Ss. Cyril and Methodius University in Skopje, Arhimedova 5, 1000 Skopje, Macedonia)

11:50 SYNTHESIS AND CHARACTERIZATION OF THE NOVEL MIXED-HALIDE PEROVSKITE DMAPbI1.5Cl1.5

Hybrid organic–inorganic perovskites are promising materials for energy-related applications owing to their tunable optoelectronic properties.1 In this work, the novel mixed-halide perovskite [(CH3)2NH2]PbI1.5Cl1.5 (DMAPbI1.5Cl1.5), within the DMAPbX3 (X = I, Br, Cl) family, was synthesized and characterized. The compound was prepared in N,N-dimethylformamide from pre-synthesized DMAPbI3 and DMAPbCl3 precursors,2 yielding a light-yellow crystalline product. Powder X-ray diffraction (PXRD) confirmed the formation of a crystalline mixed-halide phase distinct from the parent compounds. Scanning electron microscopy (SEM) revealed porous aggregated microcrystals, while energy-dispersive X-ray spectroscopy (EDX) confirmed an approximately 1:1 atomic ratio of iodine to chlorine, consistent with the targeted composition. Infrared and Raman spectroscopy confirmed the structural integrity of both the organic cation and the metal-halide framework. Cyclic voltammetry performed in dichloromethane containing tetrabutylammonium perchlorate (TBAPC) as the supporting electrolyte revealed redox activity and progressive current decay during successive scans, indicating partial electrochemical degradation of the compound.

Keywords: DMAPbI1.5Cl1.5, mixed-halide perovskite, PXRD, SEM-EDX, vibrational spectroscopy, cyclic voltammetry

Speaker: Jeta Sela (Department of Chemistry, Faculty of Natural Sciences and Mathematics, University of Tetovo, Tetovo, North Macedonia)

11:55 STRUCTURE-PROPERTY RELATIONSHIP AND PLASMON-ENHANCED PHOTOLUMINESCENCE IN Ag@Ag2O CORE-SHELL NANOPARTICLE THIN FILMS

PSSE (Scientific Section)

STRUCTURE-PROPERTY RELATIONSHIP AND PLASMON-ENHANCED PHOTOLUMINESCENCE IN Ag@Ag2O CORE-SHELL NANOPARTICLE THIN FILMS

Meri Sokolovska1, Rola Moussa2, Ljupcho Pejov1, Vlado Lazarov2, Biljana Pejova1
e-mail: merisokolovska@yahoo.com

1Institute of Chemistry, Faculty of Natural Sciences and Mathematics,
SS Cyril and Methodius University, Skopje, Macedonia
2School of Physics Engineering and Technology, University of York, York, YO10 5DD, UK

Silver/silver oxide (Ag@Ag2O) core-shell nanoparticles have attracted considerable attention due to their unique combination of plasmonic and semiconducting properties, making them promising materials for applications in sensing, photocatalysis and optoelectronics. In this work, Ag@Ag2O NP thin films were synthesized and systematically characterized to investigate the relationship between their structural, morphological, optical and photoluminescence properties.
The crystal structure and phase composition were examined by X-ray diffraction (XRD) and selected area electron diffraction (SAED), confirming the coexistence of metallic Ag and Ag2O phases. Raman spectroscopy revealed characteristic vibrational modes associated with Ag2O and provided additional evidence of the composite Ag/Ag2O structure. The enhanced Raman response observed from the nanostructured thin films indicates the presence of strong localized electromagnetic fields generated by the Ag component, highlighting the potential of the films as Surface-Enhanced Raman Scattering (SERS) active substrates. Transmission electron microscopy (TEM) revealed the formation of nanoparticles with a distinct core-shell architecture, while scanning electron microscopy (SEM) provided information on particle morphology. Atomic force microscopy (AFM) was employed to analyse the surface topography and nanoscale roughness of deposited NP thin films.
The optical properties were investigated using UV-Vis spectroscopy, revealing a pronounced localized surface plasmon resonance (LSPR) associated with the Ag core. Photoluminescence measurements demonstrated a significant enhancement of the emission intensity compared to pure Ag2O nanostructures. The observed enhancement is attributed to the coupling between the semiconductor excitonic transitions of Ag2O shell and the localized plasmonic field generated by the Ag core.
The results provide valuable insights into the structure-property relationships governing the optical response of Ag@Ag2O nanostructures and highlight their potential for plasmon-enhanced photonic, sensing and SERS applications.

Keywords: Ag@Ag2O nanoparticles, core-shell nanostructures, plasmonics, SERS substrates, photoluminescence enhancement, XRD, TEM, SEM, AFM.

Speaker: Meri Sokolovska (Ss. Cyril and Methodius University in Skopje, Faculty of Natural Sciences and Mathematics, Arhimedova 5, 1000 Skopje, Macedonia)

12:00 SYNTHESIS, CHARACTERIZATION, AND ELECTROCATALYTIC PROPERTIES OF Pr1-xErxFeO3 (x = 0, 0.2, 0.4, or 1)

Lanthanide-based perovskites have attracted considerable attention due to their structural versatility and tunable physical and chemical properties, making them promising materials for catalytic and electrochemical applications.1
In this work, the results of synthesis, characterization, and detailed electrochemical investigations of complex perovskites with the general formula Pr1xErxFeO3 (x = 0, 0.2, 0.4, or 1) are presented. These compounds are synthesized using the sol-gel combustion method, employing citric acid as fuel and chelating agent, under controlled temperature and pH conditions. The obtained samples are identified and characterized using powder X-Ray diffraction, infrared, and Raman spectroscopy, while their electrochemical properties are investigated using cyclic staircase voltammetry in different electrolytes (phosphate buffer, KNO3, and KCl) on a glassy-carbon working electrode, modified with Nafion and corresponding perovskite.
The X-Ray diffraction patterns confirmed the formation of single-phase perovskites with high purity and crystallinity. The diffraction patterns exhibit the same sequence of diffraction maxima with slight shifts in their 2θ positions, indicating that the obtained compounds are isostructural. All of them are orthorhombic and crystallize within the space group Pnma.
The recorded IR and Raman spectra confirmed the partial substitution of praseodymium with erbium and the formation of PrO and ErO bonds in the substituted perovskites. The incorporation of the smaller Er3+ in the place of the larger Pr3+ leads to a decrease in the lattice parameters, causing a shift of the vibrational modes.
Electrochemical investigations showed that the synthesized perovskites are electrochemically stable and exhibit significant electrocatalytic activity toward the reduction of dissolved oxygen. Among the investigated materials, PrFeO3 displayed the highest catalytic activity. The results indicate that the electrocatalytic properties are strongly influenced by the composition of the material and the experimental conditions.

Keywords: complex perovskites, sol-gel combustion, X-ray powder diffraction, infrared spectroscopy, Raman spectroscopy, cyclic voltammetry

References:
1. Chouhan М., et al.; Recent advances in rare-earth orthoferrites: Synthesis, dielectric-magnetic properties, and multifunctional applications, Ceram. Int. 2026, 52, 2485724877.

Speaker: Sofija Popovska Blazhevska (Institute of Chemistry, Faculty of Natural Sciences and Mathematics, “Ss. Cyril and Methodius“ University in Skopje, N. Macedonia)

12:05 SYNTHESIS AND INVESTIGATION OF La1xErxMn0.5Fe0.5O3 (x = 0.2 and 0.4) COMPLEX PEROVSKITES

In recent decades, perovskite-type ceramic materials, with general formula ABO3, have attracted considerable attention due to their significant electrical, optical, magnetic and catalytic properties. Among them, mixed-cation perovskites containing two different lanthanide ions at the A-site and two transition-metal ions at the B-site have attracted particular attention because their structural and functional properties can be effectively tuned through cation substitution. In this work, the synthesis and characterization of La1xErxMn0.5Fe0.5O3 (x =0.2 or 0.4) are presented.
These compounds were synthesized by the sol-gel combustion method using citric acid as fuel, while the pH value of the precursor solution was adjusted with ammonia. The obtained perovskite precursors were calcined at 900 °C for 8 hours to obtain the crystalline perovskite phase.
Powder X-ray diffraction (PXRD) confirmed the successful formation of single-phase perovskites with high phase purity and crystallinity, and revealed a systematic shift of the diffraction peaks with increasing of Er3+ content.
The morphology and the verification of the stoichiometry of the synthesized perovskites were performed by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDX analysis). The EDX results showed good agreement with the proposed composition. SEM micrographs revealed a typical sponge-like porous morphology characteristic for perovskites obtained by sol-gel combustion method.
In addition to structural investigations, Fourier-transform infrared (FTIR) in the mid- and far-IR regions confirmed the presence of characteristic stretching and bending vibrations of Mn/Fe–O, and Ln/Er–O. The Raman spectra of both compositions exhibit similar vibrational features in the 200–700 cm⁻¹ region, indicating similar local environments around the (Mn,Fe)O6 octahedra. The observed broad Raman bands suggest the presence of local structural disorder and distortion of the (Mn,Fe)O6 octahedra, most likely arising from the Jahn–Teller activity of Mn3+ ions together with the random distribution of Mn and Fe cations over the B-sites of the perovskite lattice.

Keywords: Complex perovskites, PXRD, SEM/EDX, FTIR, Raman spectroscopy

Speaker: Ms Cvetanka Trajkovska (Institute of Chemistry, Faculty for Natural Sciences and Mathematics , University "Ss. Cyril and Methodius", Skopje, North Macedoina)

12:10 Structural Dynamics of SsbA from Streptomyces coelicolor by Hydrogen-Deuterium Exchange Mass Spectrometry

Single-stranded DNA-binding proteins (SSBs) are essential for genome maintenance across all domains of life, protecting transiently exposed single-stranded DNA during replication, recombination, and repair. While the crystal structure and biophysical properties of SsbA from Streptomyces coelicolor have been characterized, direct information on its solution-phase conformational dynamics has been lacking.
In this study, hydrogen-deuterium exchange mass spectrometry (HDX-MS) was used to probe the conformational dynamics of free SsbA in physiological conditions. Deuterium labeling was performed at five time points (10 s, 1 min, 20 min, 1 h, 4 h). Two proteolytic strategies were used to generate overlapping peptide maps, and data were analyzed using HDExaminer software, yielding approximately 70% sequence coverage. Regions corresponding to the N-terminal His-tag (residues 1–9) and portions of the C-terminal region (residues 152–211), which includes glycine rich region and acidic C-tip (DEPPF) were not covered, consistent with known challenges in peptide identification within low-complexity sequences
The N-terminal OB-fold domain, responsible for ssDNA binding, showed a heterogeneous exchange pattern, with the highest deuterium uptake observed in the region spanning residues 26–44, and additional regions of elevated exchange around residues 60–66 and 72–89, revealing locally flexible or solvent-exposed segments. In contrast, the glycine-rich IDL region (residues ~121–151), previously described as intrinsically disordered, exhibited consistently low deuterium uptake across all time points, suggesting reduced solvent accessibility in the free state relative to that expected for a fully disordered linker. This observation is consistent with previously reported hydrodynamic data suggesting a more globular conformation of the SsbA C-domain, and may reflect self-association or condensate-forming behavior proposed for this protein.
These findings provide the first direct evidence of the conformational dynamics of free SsbA in solution and establish a baseline for future comparative HDX-MS studies.
Keywords: SsbA, HDX-MS, Streptomyces coelicolor, conformational dynamics

Speaker: Veronika Gijovska

12:15 Quantitative Evaluation of Nutritional and Safety-Relevant Elements in Sesame Seeds Using LIBS

Laser-induced breakdown spectroscopy (LIBS) was employed to perform rapid multielemental analysis of sesame (Sesamum indicum L.) seeds, focusing on both nutritional and safety-relevant elements. Pressed sesame pellets were analyzed under optimized TEA CO2 laser conditions, while inductively coupled plasma–optical emission spectrometry (ICP–OES) measurements supported calibration and ensured reliable quantification, consistent with previously developed LIBS methodologies for plant-based matrices1. Major nutrients (K, P) and safety-relevant elements (Sr, Al) were quantitatively determined. Additional major and trace elements were also identified, providing a comprehensive elemental profile. The oil-rich, compact matrix contributed to stable plasma formation, enhancing signal reproducibility and analytical precision. These results demonstrate that LIBS offers a fast and practical approach for multielemental profiling of sesame seeds, supporting nutritional evaluation and food safety monitoring, and highlight its potential applicability to other oil-rich plant-based materials.
Keywords: laser-induced breakdown spectroscopy (LIBS); sesame; quantitative analysis; nutritional profiling; food safety; ICP–OES calibration; oil-rich matrix
Acknowledgments
The research was funded by the Ministry of Education, Science and Technological Development of the Republic of Serbia, Contract numbers: 451-03-33/2026-03/200017.
References:
1. Ranković, D.; Savić, M.; Stojiljković, M.; Ristić, M.; Luchkouski, V.V.; Đorđević, N.; Chumakov, A.N. Methodological Approach to LIBS Elemental Analysis and Plasma Characterization of Quinoa and Amaranth Pseudocereals Using a TEA CO₂ Laser. Foods 2025, 14, 4199. https://doi.org/10.3390/foods14244199

Speaker: Dr Marjetka Savić (Institute of Nuclear Sciences ''Vinča'', University of Belgrade, National Institute of the Republic of Serbia)

28-SCTM-e-poster Sesame Seeds.pptx

12:20 Plasma Properties and Multielemental Profiling of Flax Seeds via TEA CO2 LIBS

Flax (Linum usitatissimum L.) seeds were studied to investigate their elemental composition and plasma characteristics, given their high oil and fiber content which creates a dense matrix affecting plasma formation and signal reproducibility. Laser-induced breakdown spectroscopy (LIBS) with a TEA CO₂ laser was applied to pressed flax seed pellets, while inductively coupled plasma–optical emission spectrometry (ICP–OES) provided calibration and reliable quantification. Calibration was performed for major nutrients and trace elements, including K, Ca, Mg, and Fe, using analyte-to-internal standard intensity ratios, demonstrating high linearity with correlation coefficients (R²) above 0.98. Emission lines of additional elements such as P, Zn, and Mn were also detected, providing a comprehensive elemental profile. Plasma diagnostics indicated an electron temperature of ~11,000 K and electron number density of ~5 × 10¹⁶ cm⁻³, confirming stable plasma conditions despite the complex flax matrix. These results highlight the applicability of TEA CO₂ LIBS for rapid, multielemental analysis of oil-rich seeds, offering valuable insight for nutritional evaluation and quality control.
Keywords: laser-induced breakdown spectroscopy (LIBS); TEA CO2 laser; flax; quantitative analysis; plasma diagnostics; matrix effects; ICP–OES calibration

Speaker: Dragan Ranković (VINCA Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, Mike Alasa 12-14, 11001 Belgrade, Serbia)

28-SCTM-e-poster Flax Seeds.pptx

12:25 Synthesis and structural characterization of Pr1-xAxCoO3 type of perovskites, A = K and Ca

Cobalt-based perovskites incorporating rare-earth elements at the A-site, partially substituted with alkali and alkaline-earth cations, have attracted considerable attention for their potential applications in solid oxide fuel cells and catalytic processes [1]. Among them, praseodymium-cobalt perovskites stand out as a particularly interesting class of materials, combining structural complexity with promising functional properties. This study focuses on their synthesis and characterization, and the influence of the rare-earth substitution on their structural stability and properties.
For the synthesis of Pr1-xAxCoO3, where A = K and Ca, the EDTA-citric acid complexing method was used. In this approach, EDTA acts as a chelating agent [2], ensuring controlled distribution of metal ions and promoting the formation of homogeneous particles with nanoscale dimensions, while citric acid is used as fuel.
The obtained perovskites were investigated by X-ray powder diffraction (XRD) and Infrared (IR) spectroscopy. The diffraction patterns confirm their purity and the degree of crystallinity, while the comparison with the unsubstituted Pr-perovskites with the corresponding metals indicates that the obtained compounds adopt an orthorhombic structure.
Further investigation and characterization was carried out using vibrational spectroscopy techniques such as IR spectroscopy in the mid-infrared (MIR) and far-infrared (FIR) region in order to probe the lattice dynamics and structural features of the obtained perovskites.

Speaker: Behima Ademovski (Postgraduate student)

12:30 Short discussion

12:40 The Effect of Doping With Sm and Nd Iions on the Chemical, Physical, Structural and Optical Properties of Geopolymers

The geopolymer obtained by the standard procedure of alkaline activation of metakaolin is doped with samarium (Sm) and neodymium (Nd) ions. The mass concentration of the dopant in both cases is 5%. After doping, the obtained materials were thermally treated at 600°C in a tube furnace in a stream of argon for 1 hour [1]. After cooling, the obtained materials were characterized using: Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HR-TEM), Fourier Transrorm Infrared Spectroscopy (FTIR) and Spectroscopic Ellipsometry (SE). SEM analysis revealed that thermal exposure induces dehydroxylation, crystallization, and sintering processes, which are reflected in both morphological (SEM) and chemical (EDS) changes. The SEM micrographs also present a low degree of geopolymerization, as evidenced by the presence of numerous unreacted particles, indicating limited dissolution of the precursor material. HR-TEM clearly shows the differences between the crystal planes in the geopolymer, the presence of Al and Si phases as well as the polycrystalline structure of the doped geopolymer even after thermal treatment [2]. FTIR spectroscopy was performed to examine the structural evolution, and confirmed existence of hydroxyl groups bonded within the gel in the range of about 3450 cm-1 was. Spectroscopic ellipsometry (SE) showed absorption of Nd and Sm dopants in the UV region in the range from 290 nm to 373 nm. It is indicative that both dopants representing rare earths show activity in the UV region.

Speaker: Dr Miloš Nenadović (Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, Mike Petrović Alasa 12-14, Vinča, Belgrade, Serbia)

12:45 Influence of samarium(III) oxide content on the physicochemical and thermal properties of metakaolin-based geopolymers

Aluminosilicate materials are widely recognized for their high mechanical strength, corrosion resistance, and thermal stability.1 In this study, metakaolin-based geopolymers were synthesized by alkali activation and doped with samarium(III) oxide (Sm2O3) in order to investigate its influence on their physicochemical and thermal properties. Two samples containing 1 wt% and 5 wt% Sm2O3 were prepared and denoted as S1 and S2, respectively. The synthesized materials were characterized using energy-dispersive X-ray fluorescence spectrometry (EDXRF)2,3, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), X-ray diffraction analysis (XRD)4, and photothermal beam deflection (PBD). The obtained results indicate that Sm2O3 was successfully incorporated into the aluminosilicate matrix, without causing significant changes in the density or porosity of the geopolymers. However, the addition of Sm2O3 altered the material's thermal response, thereby enhancing thermal conductivity. These findings suggest that Sm2O3-doped metakaolin-based geopolymers may be considered promising candidates for applications requiring improved thermal stability and thermal management, including potential use as functional insulating materials.

Speaker: Dr Sanja Knežević (Department of Materials, Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, Mike Petrović Alasa 12-14, Vinča, Belgrade, Serbia)

12:50 Effect of Wood Ash Addition on the High-Temperature Performance of Alkali-Activated Fly Ash Materials

Alkali-activated fly ash-based materials have attracted considerable attention as sustainable alternative binders due to their ability to partially replace ordinary Portland cement while exhibiting favorable mechanical properties, durability, and resistance to aggressive environmental conditions. Furthermore, the investigation of alkali-activated materials at temperatures exceeding 1000 °C is essential for assessing their thermal stability, phase evolution, and microstructural transformations, thereby providing valuable insights into their potential application as high-performance binders and refractory materials under extreme thermal conditions. In this study, two systems were prepared: pure fly ash (FA) and a blend of wood ash (WA) and fly ash (10 wt.% WA and 90 wt.% FA), which were subsequently subjected to alkali activation to enhance precursor reactivity through their calcium- and alkali-rich composition. The high-temperature behavior of fly ash and fly ash–wood ash alkali activated materials was evaluated following thermal treatment at 1000, 1100, and 1200 °C. X-ray diffraction analysis revealed the formation of thermally stable crystalline phases, including nepheline, quartz, and gehlenite in both systems, while albite was additionally identified in the FA–WA samples. Both alkali activated systems maintained structural stability up to 1100 °C; however, significant degradation and collapse of the formed structural network were observed at 1200 °C. Scanning electron microscopy demonstrated progressive densification, reduced porosity, and the transformation of the initially amorphous geopolymeric matrix into a ceramic-like structure with increasing temperature. These findings highlight the influence of wood ash incorporation on phase development and microstructural evolution, as well as the high-temperature performance of alkali-activated fly ash-based materials.

Keywords: Fly ash; Wood ash; Alkali-activated materials; High-temperature treatment; Thermal stability; Microstructural evolution
References:
Provis, J. L. Geopolymers and other alkali-activated materials: Why, how, and what? Materials and Structures 2014, 47(1–2), 11–25.
Kljajević, LJ, Marković, S., Mladenović Nikolić, N., Nenadović, M., Mirković, M., Pavlović, V., Bučevac, D., Nenadović, S. Tailoring fly ash geopolymer ceramics: The influence of alkaline activation and thermal treatment on structure and phase transformation, Ceramics International 2026, 52(5), 6342-6355, https://doi.org/10.1016/j.ceramint.2025.12.390

Speaker: Dr Ljiljana Kljajević (Department of Materials, Vinča Institute of Nuclear Sciences-National Institute of the Republic of Serbia, University of Belgrade)

12:55 STRUCTURAL AND MORPHOLOGICAL EVALUATION OF GEOPOLYMER–PA12 HYBRID COMPOSITES

This research addresses the synthesis and characterization of geopolymer–PA12 composites developed to enhance material performance. Two systems were developed: geopolymer–PA 2200 (GP_2200) and geopolymer–PA 3200 GF reinforced with glass beads (GP_3200 GF). Structural and morphological characterization was performed using XRD, FTIR, and SEM techniques. XRD confirmed the amorphous nature of the geopolymer and the semi-crystalline structure of PA12, while composite patterns exhibited features of both phases. FTIR spectra indicated the presence of characteristic functional groups of each component with no significant chemical changes.
The results indicate that the geopolymer and PA12 phases remain chemically distinct, interacting only at their interfaces through physical and morphological effects. In the glass bead–modified composite (GP_3200 GF), the silicon content increased, but no major structural changes were observed in either the matrix or the composite. A key challenge, however, is the poor compatibility between the inorganic geopolymer matrix and the organic PA12 phase. To improve interfacial bonding and achieve better phase integration, adjustments to processing conditions and the use of compatibilizers or surface treatments may be necessary.
Keywords: Geopolymer composites; Polyamide 12; Hybrid materials; Glass bead reinforcement; Interfacial bonding; Morphological analysis

References:
(1) M. Dojčinović, O. Erić-Cekić, I. Svetel, S. Ćirić-Kostić, N. Bogojević, Cavitation resistance of the material PA 3200 GF produced by selective laser sintering, Science of Sintering, 55(00): 11-11 (2023), DOI: 10.2298/SOS220522011D
(2) Y. Liu, L. Zhu, L. Zhou, Y. Li, Microstructure and mechanical properties of reinforced polyamide 12 composites prepared by laser additive manufacturing, Rapid Prototyping Journal, 25(6), (2019) 1127–1134. https://doi.org/10.1108/RPJ-08-2018-0220

Speaker: Dr Jelena Gulicovski (Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia)

13:00 Effect of MgO on the luminescent properties of SiO2-B2O3-Eu2O3 sol-gel glasses

The sol-gel method has a number of advantages over traditional high-temperature synthesis methods. The resulting materials exhibit high purity, homogeneity of nanosized particles, thermal stability, and chemical resistance. The advantages of the method are mainly expressed in the easy control over the structure and properties of the obtained glasses, as well as the low synthesis temperature.
The rare earth elements are of particular interest due to their excellent optical properties when incorporated into the glass matrix. Alkaline earth elements, when added to the glass matrix, improve the thermal stability and optical activity of rare-earth-doped sol-gel glasses.
In this work, the sol-gel process was used to synthesize a series of Eu-doped silica-boron glasses, and their luminescent properties were investigated both prior to and following MgO incorporation.
Several techniques were used to analyze the structural and optical properties of the as-obtained samples. DTA was employed to gain information about their thermal stability. IR spectroscopy was used to identify the vibrations of the structural units, while UV–Vis spectroscopy and photoluminescence spectrometer were carried out to investigate the optical properties of the synthesized materials. XRD and SEM-EDS were used to characterize the structure and surface morphology of the glass samples.
Because of their excellent optical properties, the investigated materials find wide application in optical and photonic devices, such as lasers, fiber optics and LED devices.

Keywords: sol-gel, glasses, luminescent properties

Acknowledgements: The authors are thankful to the “National Center of Excellence Mechatronics and Clean Tecnologies” for the experimental work supported by the European Regional Development Fund under the “Research Innovation and Digitization for Smart Transformation” program 2021–2027. The research equipment used was from the distributed research infrastructure INFRAMAT, which was supported by the Bulgarian Ministry of Education and Science under contract.

Speaker: Hristo Lalkovski (Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences)

13:05 CHARACTERIZATION OF HYDROGEN BLISTERING IN A LOW-CARBON STEEL STORAGE TANK

Hydrogen damage in the shape of blistering was noticed on the first shell course of a low-carbon steel atmospheric storage tank for petroleum products. The blisters were identified both on the internal and external surfaces of the plates, whereas no blistering was observed on the remaining shell courses. To investigate the influence of the blistering on the structural integrity of the tank shell, samples were taken out from areas of the plates affected with blisters and without any visible blistering. Tensile and bend tests were performed on the samples, as well as metallography and chemical composition analysis.

The investigation showed reduced mechanical properties, with both the ultimate tensile strength (Rm) and elongation (A) being lower than the standard defined values for low-carbon steel grade VSt3ps6. The bend test yielded visible cracks on the specimen during a bending angle <90o. The chemical composition analysis showed slight differences in the blistered and non-blistered samples, most notably higher content of S and P on the blistered surface. Comparing the obtained values with the chemical composition of the steel grade VSt3ps6 revealed that while the analyzed samples were mostly within the standard specifications, the S and Si content in the blistered area was slightly above the defined limits, while the Mn content was on the upper limit. These findings are in line with the conditions required for hydrogen damage, as both MnS inclusions and segregation of P along the grain boundaries present hydrogen trapping sites. The metallography revealed crack initiation sites on the edges of the blister, consistent with hydrogen-induced blistering, as well as visible presence of non-metallic inclusions.

The results revealed significant degradation caused by hydrogen, manifested by deterioration of the mechanical properties and alterations in the chemical composition of the steel. The research demonstrated that the combined application of mechanical testing, chemical composition analysis, and metallographic examination constitutes an effective approach for the detection and characterization of hydrogen damage in low-carbon steel atmospheric storage tanks. Furthermore, the findings provide valuable insight into the mechanisms governing hydrogen blister formation and establish a basis for future investigations aimed at determining the root causes of hydrogen-induced blistering.

Keywords: hydrogen blistering, low-carbon steel, mechanical properties

Speaker: Mr Andrej Češnovar (OKTA AD, 1 Str. 25 Miladinovci, 1000 Skopje, Republic of N. Macedonia)

ICTM-P7-CHARACTERIZATION OF HYDROGEN BLISTERING IN A LOW-CARBON STEEL STORAGE TANK.pptx

13:10 APPLICATION OF STATISTICAL TOOLS FOR TREND ANALYSIS OF NON-CONFORMITIES: EXPERIENCE FROM ALKALOID AD SKOPJE

In the pharmaceutical industry, managing non-conformities is not only a regulatory requirement, but also essential for maintaining product quality and patient safety. As processes become more complex, there is a growing need to move from simple deviation tracking to a more structured and data-driven approach. Statistical tools play an important role in this transition by enabling better understanding of process behavior and early identification of potential risks.
At Alkaloid AD Skopje, statistical analysis is integrated into the quality management system as part of routine deviation management. The objective is not only to document deviations, but to analyze them systematically over time in order to detect recurring patterns and identify areas for improvement.
One of the main approaches is the use of trend and control charts. These tools help visualize the frequency and distribution of non-conformities and allow teams to distinguish between normal variability and signals that may indicate underlying issues. Deviations are categorized and grouped based on type, process stage, or potential cause. Correlation analysis is also used to explore possible relationships between process parameters and deviations, such as the impact of environmental conditions or raw material variability.
Experience at Alkaloid demonstrates that applying statistical tools for trend analysis helps identify meaningful patterns, minimizes repeated deviations, and contributes to continuous improvement aligned with GMP and ICH expectations.

Speaker: Biljana Dimovska (Alkaloid AD Skopje)

13:15 ROOT CAUSE ANALYSIS (RCA) AND CORRECTIVE ACTION/IMPROVEMENT ACTION (CAIA) AS KEY TOOLS IN MANAGEMENT OF NON-CONFORMITIES

The pharmaceutical industry operates under strict regulatory frameworks to ensure that medicinal products meet the highest standards of quality, safety, and efficacy of the products1. Effective management of non-conformities in the pharmaceutical industry is essential for ensuring product quality, patient safety, and regulatory compliance.
While reporting of any nonconformity is mandatory, the key objective is identifying root causes and preventing recurrence. Root Cause Analysis (RCA) and Corrective and Preventive Actions (CAPA) are therefore fundamental elements of the pharmaceutical quality system2 as part of lifecycle management 3.
This study focuses on the most common tool used in Alkaloid AD Skopje, Ishikawa Fishbone Diagram and 5Whys, as root cause analysis as important and powerful methods for resolving cause in the investigations and defining appropriate corrective action. RCA and CAPA represent essential tools for managing non-conformities in the pharmaceutical industry and preventing their recurrence. Based on the performed root cause identification, CAIA is implemented through clearly defined actions, tracking, and effectiveness verification. Risk-based thinking ensures proportionality of investigations and actions 4.
The integration of RCA findings into CAPA strategies enables organizations to eliminate root causes effectively, prevent recurrence, and strengthen process robustness.
Keywords: Root cause analysis (RCA), Fishbone diagram (Ishikawa), 5 Whys, Corrective action/Improvement action (CAIA), Non - conformities

References:

1. Eudralex The Rules Governing Medicinal Products in the European Union Volume 4, EU Guidelines for GMP for Medicinal Products for Human and Veterinary Use- Chapter 1, Pharmaceutical Quality System. 2013
2. ICH Q10: Pharmaceutical quality system. 2008
3. ICH Q8(R2): Pharmaceutical development. 2009
4. ICH Q9(R1): Quality Risk Management. 2023

Speaker: Adrijana Nosacheva Trajkovska (Alkaloid AD Skopje)

11:40 → 13:40 Parrallel E-poster Presentations (2S)

11:40 Thermal and Fire Properties of Epoxy Composites with Melamine-Based Flame Retardants

Epoxy resins are widely used polymeric materials owing to their excellent mechanical strength, chemical resistance, and adhesion properties. However, their relatively high flammability restricts their use in areas where improved fire safety is required. Therefore, modifying epoxy systems with effective flame-retardant additives is an important area of research. Among the various flame-retardant systems available, those containing phosphorus and nitrogen have attracted considerable attention. Melamine-based phosphates in particular are considered promising additives, as they promote char formation and reduce heat release during combustion1-3.
This study examined the modification of epoxy composites crosslinked with amine hardeners using melamine phosphate flame-retardant additives. These modifiers were obtained through reactions between melamine and selected phosphorus derivatives. Additionally, a hybrid flame-retardant system containing melamine phosphate and hydrated zinc borate was prepared by mechanical mixing. These additives were then incorporated into epoxy resin systems to obtain polymer composites with enhanced flame-retardant properties. Thermal resistance (DSC and TGA) and flammability tests were also conducted to evaluate the thermal stability and fire behaviour of the prepared epoxy composites.
Keywords: epoxy resin, melamine, composites, thermal resistance, fire properties.
References
1. P. Müller, B. Schartel, Melamine poly(metal phosphates) as flame retardant in epoxy resin: Performance, modes of action, and synergy, J. Appl. Polym. Sci. 2016 (133) 24, 43549.
2. D. Jia, J. Yang, J. He, X. Li, R. Yang, Melamine-based polyol containing phosphonate and alkynyl groups and its application in rigid polyurethane foam, J. Mater. Sci. 2021 (56) 870–885.
3. P. Zheng, H. Zhao, Y. Meng, J. Li, Q. You, Q. Liu, Melamine-based biomass-containing P/N synergistic flame retardants confer superb flame retardancy and toughness to epoxy resins, Prog. Org. Coat. 2025 (198) 108927.

Speaker: Prof. BEATA PODKOSCIELNA (Maria Curie-Sklodowska University)

11:45 INFLUENCE OF SPIN COATING PARAMETERS ON β PHASE FORMATION IN PVDF THIN FILMS DEPOSITED ON ITO SUBSTRATES: AN ATR-FTIR STUDY

Poly(vinylidene fluoride) (PVDF) is one of the most attractive electroactive polymers due to its piezoelectric, pyroelectric, and ferroelectric properties, which are strongly dependent on the content of the polar β crystalline phase. The development of a high β phase content is highly sensitive to processing conditions and post processing treatments.
The spin coating method is one of the promising routes for obtaining thin films with a high content of β phase.
In this study, the influence of molar mass, solution concentration, and spin-coating speed on the β phase content of PVDF thin films was systematically investigated. Three PVDF samples with low, medium, and high molar mass (with different concentrations in DMF/Ac.) were used in this research. Thin films were deposited onto indium tin oxide (ITO) coated glass substrates by spin coating at rotational speeds between 1000 and 5000 rpm. The crystalline phase composition was analyzed by Fourier Transform Infrared Spectroscopy (FTIR). The experimental design enabled evaluation of the individual and combined effects of molar mass, solution concentration, and spin-coating speed on β crystal phase development. Variations in solution viscosity and chain entanglement associated with molar mass, together with differences in centrifugal stretching and solvent evaporation rates during spin coating, were found to influence the crystallization behavior of PVDF.
The results provide valuable insights into the optimization of processing conditions for enhancing β phase formation in PVDF thin films. The findings contribute to the development of high performance PVDF based piezoelectric and ferroelectric devices, fabricated through scalable solution processing techniques.

Speaker: Aleksandar Chukalevski (Ss Cyril and Methodius University, Faculty of Technology and Metallurgy in Skopje)

11:50 DEVELOPMENT OF WATERBORNE POLYMER NANOCOMPOSITES WITH MWCNT/Ag HYBRIDS FOR EMI SHIELDING APPLICATIONS

Waterborne polymer nanocomposites have attracted considerable attention as sustainable alternatives to solvent-based materials for electromagnetic interference (EMI) shielding applications 1,2. In this study, nanocomposite films based on a poly(methyl methacrylate-co-butyl acrylate) matrix synthesized via miniemulsion polymerization were reinforced with multi-walled carbon nanotubes (MWCNTs) and silver-decorated MWCNT (MWCNT/Ag) hybrid fillers prepared in different mass ratios. FTIR spectroscopy confirmed the successful incorporation of the conductive fillers into the polymer matrix. The mechanical properties were assessed by tensile testing, with the MWCNT/Ag-containing nanocomposites exhibiting increased toughness compared with the neat polymer. The incorporation of conductive fillers resulted in electrical conductivities on the order of 10⁻⁷ S/cm, while the surface properties remained relatively stable, with water contact angles ranging from 71° to 83°. EMI shielding measurements showed improved attenuation for the MWCNT/Ag-containing nanocomposites, with the highest shielding effectiveness observed for the 0.5 wt% 1:1 MWCNT:Ag formulation. Overall, the developed waterborne nanocomposite coatings show promising potential as lightweight and environmentally friendly materials for EMI shielding applications.

Keywords: waterborne nanocomposites, miniemulsion polymerization, MWCNT/Ag hybrids, electromagnetic interference shielding.

References:
1. Xing, D.; Lu, L.; Xie, Y.; Tang, Y.; Teh, K. S. Highly Flexible and Ultra-Thin Carbon-Fabric/Ag/Waterborne Polyurethane Film for Ultra-Efficient EMI Shielding. Mater. Des. 2020, 185, 108227. https://doi.org/10.1016/j.matdes.2019.108227.
2. Jia, Y.; Sun, R.; Pan, Y.; Wang, X.; Zhai, Z.; Min, Z.; et al. Flexible and Thin Multifunctional Waterborne Polyurethane/Ag Film for High-Efficiency Electromagnetic Interference Shielding, Electro-Thermal and Strain Sensing Performances. Compos. Part B Eng. 2021, 210, 108668. https://doi.org/10.1016/j.compositesb.2021.108668.

Speaker: Ms Andrea Petanova (Ss. Cyril and Methodius University in Skopje, Faculty of Technology and Metallurgy, Skopje, Macedonia)

11:55 ANTI-INFLAMMATORY EFFECTS OF GRAPE SKIN EXTRACT-LOADED HYDROGELS IN CARRAGEENAN-INDUCED PAW EDEMA IN RATS

Introduction: Inflammation is a response to tissue injury characterized by swelling, redness, and pain. Although conventional anti-inflammatory drugs are effective, polyphenol-rich natural products may offer a safer alternative. Grape skin extracts are rich in compounds that exhibit antioxidant and anti-inflammatory activities1, however, their therapeutic potential following incorporation into topical formulations remains insufficiently investigated. This study evaluated the anti-inflammatory effects of hydrogels containing grape skin extracts obtained from Cabernet Sauvignon (E1) and Shiraz (E2) in a rat model of carrageenan-induced paw edema.
Methodology: Extracts (8 mg/mL) were incorporated into alginate-gelatin hydrogels containing 3% of each polymer (1:1), followed by homogenization, sonication, freezing, cross-linking with calcium chloride, and drying. Wistar albino rats were assigned to four groups (n=4): control (CTRL), hydrogel base (HB), E1, and E2. Paw edema was induced by carrageenan injection, the formulations were applied immediately, and paw thickness was measured at baseline and after 1, 2, 3, and 4 hours.
Results: CTRL animals exhibited swelling, peaking 1–2 hours after injection and declining slowly afterwards. HB produced only a minor reduction in edema. Both extract-loaded hydrogels reduced paw swelling, with E1 showing the strongest and consistent effect, lowering peak edema and accelerating recovery toward baseline by hour 4. E2 demonstrated a moderate effect that exceeded that of HB.
Conclusion: These findings support investigation of grape skin extracts as bioactive components of topical formulations for inflammation and wound healing.
Keywords: Grape skin extract, hydrogel, anti-inflammatory activity.

Speaker: Marko Simic (Department of Pharmacy, Faculty of Medical Sciences, University of Kragujevac, Kragujevac, Serbia)

12:00 Development of Halochromic Nanofibrous Wound Dressings for Real-Time pH Monitoring and Wound Healing Applications

The reduction of infection risk, acceleration of the wound healing process, and monitoring of changes in the wound environment are of great importance in the treatment of chronic wounds. However, infection and the associated pH changes in chronic wounds may prolong the healing process and increase the risk of complications. Therefore, there is growing interest in the development of smart wound dressings capable of real-time monitoring of pH changes and responding to changes in the wound environment.1,2 In this study, PLA-based films and electrospun nanofibrous wound dressings containing the halochromic dye Alpha-Naphtholphthalein were developed. For optimization, PLA-based films containing different concentrations of PEG6000 were prepared and evaluated before the fabrication of nanofibrous structures. The results demonstrated a distinct color change under basic conditions. Based on these findings, nanofibrous structures were fabricated using the electrospinning technique with the selected formulations. ³ The produced nanofibers were morphologically characterized by scanning electron microscopy (SEM). The obtained results indicate that the developed halochromic nanofibrous structures have the potential to enable the visual monitoring of pH changes in the wound environment. In the next stage of the study, nanofibrous structures containing bioactive agents will be developed, and their wound healing-supporting properties will be investigated. Ultimately, this study aims to develop multifunctional smart wound dressings capable of both real-time pH monitoring and supporting the wound healing process.
“This work was supported by Çanakkale Onsekiz Mart University The Scientific Research Coordination Unit, Project number: FYL-2025-5327”. The authors would like to thank the Scientific Research Projects Coordination Unit of Çanakkale Onsekiz Mart University (BAP) for its financial support.

Speaker: Buse Suna (Çanakkale 18 Mart Üniversitesi)

12:05 LAYER-BY-LAYER ASSEMBLY OF LIGNIN-DERIVED BIOCHAR/POLYMER COMPOSITE FILMS FOR SELECTIVE ADSORPTION OF 2,4-DIMETHYLBENZOIC ACID

Activated biochar was prepared from lignin by chemical activation with NaOH followed by carbonization at 600 °C for 2 h. The resulting biochar was washed with 1 M HCl and deionized water, dried, and dispersed in water using poly(vinyl pyrrolidone) (PVP) as a surfactant. Multilayer composite films were fabricated by combining a poly(methyl methacrylate-co-butyl methacrylate), p(MMA/BMA) (30/70 wt/wt), matrix with the lignin-derived biochar using a layer-by-layer (LbL) assembly approach. Spin coating deposition enabled the sequential formation of polymer (P) and biochar (B) layers, producing films with different architectures (P, B, P-B, P-B-P, and P-B-P-B). After each deposition step, the films were rinsed to remove loosely bound material and dried at 45 °C to ensure uniform layer formation. The optical properties of the multilayer films were investigated by UV–Vis spectroscopy, revealing characteristic π–π and π–π transitions of the polymer matrix in the UV region. Increasing the number of deposited layers, particularly those containing biochar, enhanced UV absorption while reducing optical transparency, indicating successful incorporation of biochar and increased surface coverage. Surface morphology examined by optical microscopy demonstrated that spin coating produced smooth and homogeneous films, with progressive encapsulation of the biochar particles by the polymer matrix as additional layers were deposited. Among all investigated architectures, the multilayer sandwich structure (P-B-P-B) exhibited the best sensing performance, showing a selective frequency decrease of 160 Hz upon exposure to a 0.02 mg/mL solution of 2,4-dimethylbenzoic acid, whereas the simpler film configurations showed no measurable response. These findings demonstrate the potential of lignin-derived biochar/polymer multilayer films as sustainable functional materials for selective adsorption and sensing applications.

Keywords: lignin-derived biochar, multilayer coatings, adsorption.

Speaker: Marija Prosheva (Faculty of Technology and Metallurgy)

12:10 EXPERIMENTAL STUDY OF CO₂ ADSORPTION KINETICS ON ZEOLITES USING THE BREAKTHROUGH CURVE METHOD

The increasing concentration of carbon dioxide (CO₂) in the atmosphere is a major contributor to global climate change, creating a growing demand for efficient carbon capture technologies. Among the available separation methods, adsorption on solid porous materials has emerged as a promising alternative due to its high selectivity, low energy consumption, and operational simplicity. Synthetic zeolites, particularly 13X and 5A, are widely used for CO₂ capture because of their developed microporous structures and favorable adsorption properties.
Although zeolite-based adsorption has been extensively studied, a detailed understanding of the effects of operating conditions on adsorption kinetics is still required for process optimization. In particular, the influence of inlet CO₂ concentration, gas flow rate, and adsorbent type on breakthrough behavior remains of significant interest.
In this study, the adsorption kinetics of CO₂ on synthetic zeolites 13X and 5A were investigated using the breakthrough curve method. Experiments were performed in a fixed-bed adsorption column packed with 22.5 g of adsorbent at a bed height of 9 cm. A CO₂–air mixture was introduced under different operating conditions, with inlet CO₂ concentrations ranging from 5.2% to 15.6% and total flow rates from 14.67 to 21.83 L min⁻¹. Outlet CO₂ concentration and temperature were continuously monitored to determine breakthrough time, saturation time, adsorbed CO₂ mass, and temperature changes during adsorption.
The results showed that increasing the inlet CO₂ concentration and gas flow rate reduced breakthrough and saturation times while increasing the adsorbed CO₂ mass. The adsorption process was accompanied by a measurable temperature rise, confirming its exothermic nature. Zeolite 13X exhibited higher adsorption capacity at CO₂ concentrations around 10%, whereas zeolite 5A showed better performance at lower CO₂ concentrations (~5%). These findings provide useful insights for the optimization of adsorption-based CO₂ capture systems.

Keywords: CO₂ adsorption, zeolites, breakthrough curves, adsorption kinetics, fixed-bed column.

Speaker: Dunja Šijaković (Innovation Center, Faculty of Technology and Metallurgy, Belgrade, Serbia)

12:15 CO₂ adsorption in a draft-tube spout–fluid bed with a hydraulic barrier

Adsorption-based CO₂ capture requires not only highly selective adsorbents, but also an efficient gas–solid contacting configuration that ensures sufficient gas residence time, effective adsorbent utilization, stable particle circulation, and enhanced heat transfer. In this work, CO₂ adsorption was investigated in a draft-tube spout-fluid bed with a hydraulic barrier. This configuration was designed to provide spatial separation between the adsorption zone and particle transport. A CO₂-containing stream was introduced into the annulus as the aeration gas, while a separate air stream was introduced at the bottom of the hydraulic barrier as the spouting gas. In the annulus, particles move downward as a moving packed bed, while the draft tube provides upward particle transport and circulation. The hydraulic barrier suppressed aeration gas bypass into the draft tube and confined adsorption to the annulus. Previous hydrodynamic investigations of this system enabled the selection of suitable geometric and operating conditions characterized by stable particle circulation, low minimum spouting gas flow rate, reduced pressure drop, and favourable gas distribution1. In this study, the influence of inlet CO₂ concentration and gas flow rates on the breakthrough behaviour was first investigated using zeolites 13X and 5A as adsorbents. Adsorption experiments were then performed under selected optimal hydrodynamic conditions. Outlet CO₂ concentration and bed temperature were measured to determine breakthrough and saturation times, temperature response, and adsorption capacity. The results show that the investigated system can be considered a hybrid gas-solid contactor, combining the favourable contact characteristics of a moving packed bed with the process flexibility of circulating particle systems. Therefore, it represents a promising platform for CO₂ capture and future adsorption-regeneration integration.

Keywords: spout-fluid bed, CO2 adsorption, breakthrough curves, zeolites.
References:
(1) Šućurović, K.; Jaćimovski, D.; Brzić, D; Đuriš, M.; Arsenijević, Z.; Kaluđerović Radoičić, T.; Bošković Vragolović, N. Pressure drop and fluid flow distribution in a modified spout-fluid bed with a draft tube and hydraulic barrier. Chemical Engineering Communications 2026, 1-18. https://doi.org/10.1080/00986445.2026.2654151

Speaker: Ms Katarina Šućurović (Institute of Chemistry, Technology and Metallurgy - National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia)

12:20 EFFECT OF PYROLYSIS TEMPERATURE ON THE LEACHING BEHAVIOR OF ENRICHED DIGESTATE BIOCHAR

This study aimed to valorize nutrient-rich wastewater from the corn starch industry by using it as a source of plant-relevant nutrients, primarily nitrogen and phosphorus, to enrich anaerobically digested sewage sludge (ADSS). ADSS obtained from the Public Utility Company “Vodovod i kanalizacija” Subotica, Serbia, was enriched with corn starch industry wastewater in a continuous packed-bed column containing approximately 100 g of digestate. The enrichment was carried out over 24 h in a cylindrical plexiglass column with an inner diameter of 40 mm and a height of 180 mm, while 0.7 L of wastewater was continuously mixed and circulated through the column using a peristaltic pump at a flow rate of 4 mL/min.
The enriched digestate was then subjected to pyrolysis at 400, 550, and 700 °C under an argon atmosphere to produce biochars with varying degrees of thermal transformation. The resulting materials were evaluated using a leaching test to determine how pyrolysis temperature affected nutrient release and the mobility of potentially toxic elements. Particular attention was given to balancing the retention of plant-relevant elements and the stabilization of hazardous elements within the carbonaceous and mineral matrix.
The results showed that pyrolysis temperature strongly influenced elemental leaching behavior. Biochars produced at higher pyrolysis temperatures, particularly 550 and 700 °C, generally showed reduced leaching of most potentially toxic elements, indicating improved stabilization within the solid matrix and enhanced environmental safety. This effect may be related to the incorporation of metals into stable carbonaceous and mineral phases. Meanwhile, the biochars retained key plant-relevant elements, including Ca, K, Mg, P, and, to a lesser extent, residual N.
Overall, the combination of nutrient enrichment and controlled pyrolysis produced a stabilized, mineral-enriched biochar with potential as a soil conditioner. These findings suggest that this approach may support the sustainable valorization of both anaerobically digested sewage sludge and nutrient-rich industrial wastewater from the corn starch industry.

Keywords: anaerobically digested sewage sludge, corn starch industry wastewater, pyrolysis, biochar, leaching test, soil conditioner

Speaker: Mihal Đuriš (University of Belgrade – Institute of Chemistry, Technology and Metallurgy – National Institute of the Republic of Serbia (ICTM))

12:25 Bismuth-Modified Wood Waste as a Sustainable Sorbent for Reactive Blue 19 Removal

Water pollution is a major environmental concern due to its negative effects on aquatic ecosystems and human health. Textile dyes are particularly problematic among water contaminants because of their widespread industrial use, complex structures, and resistance to degradation, because their release into aquatic environments can reduce light penetration, disrupt aquatic organisms, and introduce potentially toxic or mutagenic substances. 1 Conventional wastewater treatment methods may be ineffective for the removal of persistent dyes, while advanced technologies often require high costs and complex operational conditions. Sorption has therefore attracted considerable interest as an efficient, cost-effective, and environmentally friendly treatment approach, particularly waste-derived materials such as wood waste represent promising sorbents.2
In this context, the present study aimed to develop a bismuth-modified wood waste sorbent and evaluate its efficiency in removing Reactive Blue 19 from aqueous solutions. The sorption performance was assessed through optimization of the sorption process by systematically investigating the influence of key operational parameters, including contact time, solution pH, pollutant concentration, initial dye concentration, and temperature, in order to determine the conditions that favor efficient dye removal. Maximal dye removal was achieved for 40 min, at pH 2, with 2 g/L sorbent dose, at 25 °C, with 300 mg/L complete dye removal indicating the high sorption efficiency and strong potential of the sorbent.

Speaker: Nena Velinov (University of Niš, Faculty of Sciences and Mathematics, Department of Chemistry)

12:30 Short discussion

12:40 Ferrite-based sorbent for efficient removal of Reactive Blue 19 dye

Environmental contamination by organic pollutants, especially reactive textile dyes, represents a serious and persistent threat to living organisms.1 Reactive Blue 19 (RB19) is a stable anionic dye containing electrophilic vinylsulfone groups, which may contribute to its toxic and mutagenic potential.2 Sorption is widely applied for dye removal from water due to its efficiency, low cost, and simple operation. Ferrites are versatile ferrimagnetic materials whose properties depend on their composition, structure, and synthesis conditions. Among them, spinel ferrites are the most common. Their chemical and thermal stability, easy synthesis, low cost, and diverse magnetic and catalytic properties make ferrites promising materials for sorption and water purification.
The zinc–manganese ferrite carbonate was synthesized by coprecipitation. Bach experiments evaluated the influence of pH, dye concentration, contact time, and sorbent dosage on RB19 removal. Sorption mechanisms were analyzed using kinetic (pseudo-first and pseudo-second order) and isotherm (Langmuir, Freundlich and Brouers–Sotolongo) models. Optimal sorption of RB19 was achieved at pH 2 and sorbent dose of 0.25 g/L, yielding a maximal sorption capacity of 1463.1 mg/g. The process is driven by electrostatic interaction between positively charged sorbent sites and the RB19 sulfonic groups, supported by Van der Waals forces. Kinetic and equilibrium studies confirm chemisorption as the dominant mechanism, with Langmuir isotherm fitting indicating a homogeneous sorption surface.

Speaker: Nena Velinov (University of Niš, Faculty of Sciences and Mathematics, Department of Chemistry)

12:45 INFLUENCE OF PHYSICAL AND CHEMICAL PARAMETERS ON THE RHEOLOGICAL PROPERTIES OF MODIFIED DISTARCH ADIPATE

Distarch adipate is a highly utilized modified starch valued for its texturizing stability. This study aims to investigate how specific physical and chemical processing variations alter its rheological profile, providing essential data for optimizing industrial-scale starch modification. Starch modification was performed in a controlled 600 mL reactor system integrated with automated stirring, temperature, pH regulation, and precise dosing. The effects of shifting parameters—specifically acetic anhydride and adipic acid concentrations, modifier preparation time/temperature, water and sulfate levels, and various mixing intervals—were comprehensively evaluated. All rheological changes were characterized using a Brabender amylograph. The resulting Brabender amylograms demonstrated that adjustments in modifier concentration and reaction temperature directly dictate the peak viscosity and gelatinization onset. The results indicate that achieving high-performance distarch adipate requires a careful balance of all components and process conditions, as a shift in a single parameter significantly alters the overall rheological behavior. The optimized starch matrix must exhibit excellent texture, acid and shear resistance, and high water-holding capacity. Mixing time and sulfate presence primarily influenced the breakdown and setback viscosity profiles. In conclusion, this work presents a systematic overview of how chemical dosing and mechanical handling inside a reactor can be adjusted to tailor the visco-elastic performance of distarch adipate. These insights allow for precise customization of starch properties for specific food and industrial formulations requiring high stability.

Keywords: distarch adipate, rheology, Brabender amylograph, water-holding capacity, process optimization.

Speaker: Darko Jaćimovski (Institute of Chemistry, Technology and Metallurgy – National Institute of the Republic of Serbia,University of Belgrade, Belgrade, Serbia)

12:50 OPTIMIZATION OF ETHANOLIC EXTRACTION CONDITIONS FROM BLUEBERRY WASTE AND IN VITRO EVALUATION OF ANTIOXIDANT POTENTIAL

Introduction: Blueberry (Vaccinium spp.) waste, a by-product of industrial fruit processing, represents a rich source of polyphenolic compounds, particularly anthocyanins, which may contribute to the antioxidant potential. Ultrasound-assisted ethanolic extraction is an efficient and eco-friendly approach for obtaining bioactive extracts from this raw material.1 The aim of this study was to optimize the extraction conditions for blueberry waste and evaluate the in vitro antioxidant potential of three obtained extracts.
Methodology: Ultrasound-assisted extraction was performed using ethanol concentrations of 40% and 60%, temperatures of 45 °C and 55 °C, and extraction times of 20–60 min. Antioxidant activity was determined by DPPH and ABTS assays (IC50, µg/mL), while total phenolic content (TPC) was determined by the Folin–Ciocalteu method (mg GAE/g DE).
Results: Extract E1 (60% EtOH, 55 °C, 30 min) exhibited the highest TPC (93.14 mg GAE/g DE), strongest ABTS activity (IC50 = 24.19 µg/mL), and favorable DPPH activity (IC50 = 304.85 µg/mL). Extracts E2 (40% EtOH, 55°C, 60 min) and E3 (60% EtOH, 45°C, 20 min) showed slightly lower but comparable antioxidant activity (DPPH IC50 = 308.65 and 322.00 µg/mL; ABTS IC50 = 40.47 and 33.60 µg/mL) and phenolic content (85.43 and 80.00 mg GAE/g DE).
Conclusion: E1 showed the most favorable overall antioxidant profile, indicating that higher ethanol concentration and temperature favored phenolic recovery and antioxidant activity within a short extraction time. E2 and E3 also demonstrated considerable antioxidant activity and phenolic content, supporting ultrasound-assisted extraction as an effective approach for blueberry waste valorization.
Keywords: Blueberry, fruit waste, ethanolic extraction, ultrasound, polyphenols.

Speaker: Djurdjina Petrovic (Center of Excellence for the Study of Redox Balance in Cardiovascular and Metabolic Disorders, 34000, Kragujevac, Serbia)

12:55 TYROSINASE-INHIBITORY POTENTIAL OF PROKUPAC GRAPE EXTRACTS: INFLUENCE OF BERRY PART AND EXTRACTION PH

Tyrosinase is a copper-dependent enzyme involved in melanin biosynthesis, and its increased activity is associated with hyperpigmentation. Due to the limitations of some synthetic inhibitors, natural polyphenol-rich plant extracts are increasingly investigated as safer alternatives. Prokupac grapes are of particular interest because of their specific phenolic profile and potential for the valorisation of local viticultural resources.
The aim of this study was to investigate the tyrosinase-inhibitory potential of extracts obtained from grape skin, pulp, and seeds of the Prokupac variety, with emphasis on the influence of extraction pH. The extracts were prepared using 50 mM buffer solutions with pH values ranging from 4.0 to 8.0. Tyrosinase activity was determined spectrophotometrically by monitoring dopachrome formation from L-DOPA at 475 nm, while inhibition was calculated in relation to a control sample without inhibitor. The dry residue of the extracts was also determined. Statistical analysis was performed using two-way ANOVA and Tukey’s post hoc test, with p < 0.05 considered significant.
The results showed that tyrosinase-inhibitory activity depended significantly on both the berry part and extraction pH. Grape skin extracts exhibited the strongest activity, with inhibition ranging approximately from 70 to 95%, while seed extracts showed moderate to high activity. Pulp extracts demonstrated considerably lower inhibitory potential. The highest inhibition was recorded at pH 6, where skin, seed, and pulp extracts inhibited tyrosinase activity by 94.81%, 78.94%, and 58.20%, respectively. The highest dry residue values were also observed at pH 6, suggesting a possible relationship between the amount of extracted compounds and biological activity.
These results indicate that Prokupac grape skin and seeds are promising sources of natural tyrosinase inhibitors. Their activity may be associated with polyphenolic compounds capable of affecting enzyme activity, including through copper ion chelation. Prokupac grape extracts therefore show potential for use as natural active ingredients in dermocosmetic formulations aimed at regulating melanogenesis and treating hyperpigmentation.

Keywords: Prokupac, grape, tyrosinase, inhibition, polyphenols, hyperpigmentation.

Speaker: Jana Cvetkovic (University of Nis, Faculty of Technology)

13:00 ORANGE PEEL ESSENTIAL OIL AS A NATURAL SOLVENT FOR PROPOLIS: DEVELOPMENT AND CHARACTERIZATION OF AN OIL-BASED FORMULATION

Propolis is a natural source of bioactive compounds, but its conventional formulations are predominantly based on ethanol or other synthetic solvents, which limits their application in certain consumer and pharmaceutical products. This study aimed to develop and characterize a natural, alcohol-free oil formulation of propolis using orange peel essential oil as a functional terpene-rich solvent. Orange peel, an agro-industrial by-product, was subjected to hydrodistillation to obtain the essential oil, which was subsequently characterized by GC–MS. The obtained orange peel oil was dominated by D-limonene (97.09%), accompanied by smaller amounts of β-pinene (1.69%), α-pinene (0.45%), sabinene (0.43%), 3-carene (0.22%), and valencene (0.08%). The propolis was dissolved in orange peel oil and the formulation was further optimized by incorporating grape seed oil as a natural carrier and diluent. HPLC analysis confirmed the presence of citral in the propolis–orange peel oil formulation at 0.944 mg/mL, while p-coumaric and ferulic acids were detected at 0.109 mg/mL each. Thermal analysis demonstrated that incorporation of grape seed oil substantially improved the thermal stability of the final formulation compared with pure orange peel oil and the propolis–orange peel oil system. Antimicrobial testing further demonstrated selective activity of the formulations against Staphylococcus aureus and Candida albicans. The developed formulation provides a natural, alcohol-free approach for incorporating propolis bioactive compounds into an oil-based system while simultaneously valorizing orange peel agro-industrial waste. The proposed product has potential applications in food supplements, cosmetics, and other natural bioactive formulations.

Keywords: propolis, D-limonene, orange peel waste, essential oil-based formulation, bioactive compounds, HPLC analysis, thermal stability, antimicrobial activity.

Acknowledgements: This work was supported by the Ministry of Science, Technological Development and Innovation of the Republic of Serbia (Contracts No. 451-03-33/2026-03/200135 and 451-03-33/2026-03/200287) and the Western Balkans Innovation Voucher Programme (WBIV Application No. 09-2789; Contract No. 09-1007), within the Horizon Europe SPIN project (Grant Agreement No. 101058873).

Speaker: Nataša Obradović (University of Belgrade, Faculty of Technology and Metallurgy)

13:05 Influence of the Addition of Pork Collagen Protein on the Particle Size Distribution in Cocoa Cream Products

Recent dietary trends indicate a growing consumer preference for high-protein diets. Confectionery products are typically characterized by low protein content and high levels of fat and sugar, making them suitable matrices for protein enrichment. Collagen, a protein derived from animal by-products such as skin and bones, represents a highly valuable ingredient due to its recognized benefits for skin, nails, and other connective tissues.
This study investigates the incorporation of collagen derived from pork skin at different concentrations (10%, 12.5%, and 15%) for the enrichment of cocoa cream products. Particle size distribution in control (C) and collagen-enriched samples (CC10, CC12.5, and CC15) was analyzed using a Mastersizer 2000 (Malvern Instruments). Measurements were conducted with the Malvern Hydro 2000µP dispersion unit, with samples dispersed in sunflower oil prior to analysis.
The results demonstrated that increasing collagen concentration resulted in a progressive increase in the volume-weighted mean diameter, D[4,3], across all collagen-enriched samples, whereas the highest value (94.051 µm) was recorded for the raw material, pork collagen powder (CP). However, in the enriched cocoa cream samples, D[4,3] values did not exceed 30 µm. Considering that the optimal particle size range (15–30 µm) is associated with the absence of a gritty mouthfeel, the addition of pork collagen did not negatively affect the sensory quality of the produced samples.

Keywords: protein, pork collagen, cocoa cream products, particle size distribution, functional food products

Acknowledgment: This work builds on the TwInSol-CECs collaboration (101059867), which also fostered the participation of the Faculty of Technology Novi Sad in the T4I project consortium (101311065). Additionally, this work is supported by the Program of the Ministry of Science, Technological Development and Innovation of the Republic of Serbia (number: 451-03-34/2026-03/ 200134 , and 451-03-33/2026-03/ 200134).

Speaker: Dr Biljana Pajin (Faculty of Technology Novi Sad, University of Novi Sad)

BFT-P4-Stožinić et al..pptx

13:10 Effect of probiotic preparations on Enterobacteriaceae and microbiological safety of raw cow’s milk

Enterobacteriaceae have been established as indicators of microbiological quality and hygiene in food processing and are therefore an important factor in ensuring microbiological quality of milk. The aim of this study was to evaluate the effect of two commercial probiotic preparations, Diastop® Probio, containing four types of lactic acid bacteria: Lactobacillus acidophilus, Streptococcus thermophilus, Bifidobacterium, and Lactobacillus delbrueckii, and NBL Probiotic ATP, containing: Lactobacillus casei, L. rhamnosus, L. plantarum and Bifidobacterium lactis, on the microbiological quality and safety of raw cow’s milk. The initial microbial load in the milk was assessed, and the probiotic preparations were subsequently applied separately on samples of milk and incubated at 42 °C for four days. Changes in total mesophilic aerobic microorganisms and Enterobacteriaceae were assessed during the incubation period through the use of Plate Count Agar (PCA) and Violet Red Bile Glucose Agar (VRBGA) medium plates correspondingly. The initial sample of milk contained 7.6 × 10⁴ CFU/mL Enterobacteriaceae and 6.0 × 10⁶ CFU/mL mesophilic aerobic microorganisms. After probiotic treatment, Enterobacteriaceae progressively decreased, with no detectable growth on VRBGA at the higher dilutions by the third day and at the lower dilutions by the fourth day. In turn, the number of mesophilic aerobic microorganisms increased during the incubation period, and it could be associated with the growth of probiotic microorganisms. Overall, the tested probiotic preparations showed potential for lowering Enterobacteriaceae counts and may enhance the microbiological quality of raw cow milk.

Speaker: Ismail Ferati (University of Tetova, Faculty of Food Technology and Nutrition)

13:15 Good GHG Reduction practices

Abstract: Reducing GHG emissions and improving waste management are key challenges for every industry. This abstract presents a practical example of GHG reduction through industrial symbiosis between ALKALOID AD Skopje1 and Elektro Sharri – Veze Sharri Group, Tetovo2.
Since 2024, ALKALOID has supplied plant-based tea production waste to Elektro Sharri’s biogas cogeneration plant, where it is used as feedstock which by anaerobic digestion process is converted to renewable energy instead of being landfilled.
Over the period 2024–2025, the diversion of 13.07 tons of organic waste resulted in the avoidance of approximately 24.8 [t] of CO₂ equivalent emissions, including a significant reduction of methane that would otherwise be generated in landfill conditions3,4,5. At the same time, this waste contributed to the generation of approximately 3.4 [MW] of renewable electricity, supporting low‑carbon energy production7,8,9.

Keywords: biological waste, anaerobic digestion process, biogas-methane cogeneration plant

References:
1 Alkaloid AD Skopje. Official Website. www.alkaloid.com.mk (accessed June 12, 2026)
2 Veze Sharri. Sustainability. www.vezesharri.com/sustainability(accessed June 12, 2026)
3 Intergovernmental Panel on Climate Change (IPCC). Waste Management. www.ipcc.ch/site/assets/uploads/2018/03/5_Waste-1.pdf (accessed June 12, 2026).
4 U.S. Environmental Protection Agency (EPA). Quantifying Methane Emissions from Landfilled Food Waste.www.epa.gov/land-research/quantifying-methane-emissions-landfilled-food-waste (accessed June 12, 2026).
5 Nature. Methane Emissions from Landfills Differentially Underestimated Worldwide.www.nature.com/articles/s41893-024-01307-9 (accessed June 12, 2026).
6 Prognos AG. Methane Emissions from Europe’s Landfills. www.prognos.com/sites/default/files/2026-03/prognos_study_methane_emissions_from_europes_landfills%20%282%29.pdf (accessed June 12, 2026).
7 International Energy Agency (IEA). Average Biogas Production Yield by Tonne of Feedstock Type. www.iea.org/data-and-statistics/charts/average-biogas-production-yield-by-tonne-of-feedstock-type (accessed June 12, 2026)
8 GreenGas Inc. Biogas Electricity Generator. www.greengasinc.com/energy/biogas-electricity-generator/(accessed June 12, 2026).
9 Energypedia. Electricity Generation from Biogas. www.energypedia.info/wiki/Electricity_Generation_from_Biogas (accessed June 12, 2026)

Speaker: Mrs Irena Mukaetova Velichkov (Alkaloid AD Skopje)

E-poster for Good GHG reduction practice.pptx

13:20 INFLUENCE OF BOTANICAL ORIGIN ON THE PHYSICOCHEMICAL PROPERTIES OF HONEYS FROM NORTH MACEDONIA

Honey quality and physicochemical properties are strongly influenced by botanical origin and are important indicators for characterization, authenticity, and market quality 1. This study evaluated pH, electrical conductivity (EC), moisture content, and dry matter in acacia (Robinia pseudoacacia) (n = 3), multifloral (n = 3), and chestnut (Castanea sativa) (n = 2) honey samples collected in North Macedonia. The pH values ranged from 3.61 to 4.79, confirming the naturally acidic character of all samples. Electrical conductivity showed the clearest differentiation among honey types, with values ranging from 0.132 to 1.097 mS/cm. Acacia honey exhibited the lowest EC values (0.132–0.136 mS/cm), multifloral honey showed intermediate values (0.412–0.616 mS/cm), whereas chestnut honey had the highest EC values (1.075–1.097 mS/cm). These results are consistent with international quality criteria, according to which most blossom honeys have EC values below 0.8 mS/cm, while chestnut honey typically exceeds this threshold 2,3. Moisture content ranged from 13.8 to 18.5%, with all samples complying with the internationally established maximum moisture content of 20% for honey, indicating satisfactory maturity and storage stability. All samples complied with the internationally established maximum moisture content of 20% for honey, indicating satisfactory maturity and storage stability 2,3. Acacia honey generally exhibited the lowest moisture content, whereas chestnut honey showed comparatively higher values, with multifloral honey exhibiting intermediate moisture content. Overall, the investigated honeys demonstrated satisfactory physicochemical quality and characteristics consistent with their declared botanical origins. Electrical conductivity was the most useful parameter for differentiating the three honey groups. These findings contribute to the characterization, quality assessment, and potential market valorization of honey produced in North Macedonia and support future authentication of regional products.

Speaker: Dr Durim Alija (Professor)

Saturday 26 September

09:00 → 09:30 CONTROLLING REACTIVITY IN MECHANOCHEMISTRY: FROM ADVANCED MOFS TO SCALABLE MATERIALS

Mechanochemistry has emerged as a sustainable and versatile platform for the synthesis of functional materials, offering solvent-free and energy-efficient alternatives to conventional synthetic approaches.1 Beyond its green metrics, mechanochemistry provides unique opportunities to control chemical reactivity by tuning parameters such as temperature, mechanical input, and reaction environment.
Here we highlight recent advances in controlling mechanochemical reactivity for the synthesis of advanced materials, including metal–organic frameworks (MOFs),2 MOF-based composites,3 and scalable inorganic–organic systems.4 Recent studies demonstrate how controlled mechanochemical methods can modulate reaction pathways, rates, and selectivity, often enabling access to products unattainable by conventional solution-based synthesis.2,3 Mechanochemical approaches have enabled precise control of composition and phase purity in porous materials, facilitating the incorporation of guest species and the formation of functional composites with tailored properties. Finally, the scalability of these processes will be discussed by examining the translation of laboratory-scale milling to continuous production methods, demonstrating improved energy efficiency, throughput, and prospects for industrial implementation.

Speaker: Dr Bahar Karadeniz (Rudjer Boskovic Institute)

09:30 → 10:00 Tracking PFAS in Water: From Monitoring to Risk Prioritisation

Per- and polyfluoroalkyl substances (PFAS) are among the most challenging contaminants of emerging concern due to their persistence, structural diversity, and complex toxicological profiles. Their widespread use has led to global occurrence in aquatic environments, while differences in physicochemical properties across the PFAS class complicate both monitoring and environmental interpretation. This lecture presents a stepwise framework for tracking PFAS in surface waters, beginning with high-resolution mass spectrometry (HRMS)-based suspect screening analysis to expand PFAS coverage beyond conventional target lists and capture known, emerging, and previously overlooked PFAS. Screening results are then linked to hazard- and exposure-based prioritisation, integrating QSAR-derived indicators of persistence, bioaccumulation, and toxicity with occurrence-related metrics such as detection frequency and concentration magnitude. This prioritisation step supports the identification of the most relevant PFAS for follow-up analysis. A subset of prioritised compounds was then selected for targeted (semi)quantification based on both prioritisation outcomes and the availability of analytical standards, enabling experimental confirmation and refinement of the assessment. The approach is illustrated through recent investigations¹ of urban-impacted river systems in Serbia, representing one of the first comprehensive PFAS assessments in this part of the Danube River Basin. Initial HRMS screening revealed additional PFAS beyond the conventional target list, including ultra-short-chain compounds i.e. trifluoroacetic acid (TFA), which has recently gained particular regulatory relevance in the EU and was often detected at higher levels than legacy PFAS. Overall, the lecture demonstrates how a workflow progressing from broad screening to prioritisation and targeted confirmation can strengthen PFAS monitoring and provide a more robust basis for environmental risk assessment and regulatory decision-making.

Speaker: Dr Igor Antić (University of Novi Sad, Faculty of Technology Novi Sad, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia)

10:00 → 10:30 Closing the Water Loop in Mineral Processing: Iimpatcos of Recycled-Process-Water on (Cu-Mo) Sulfide Mineral Flotation

Flotation remains the primary technique for extracting valuable sulphide minerals, but its reliance on water presents a massive challenge amid rising global water scarcity and environmental restrictions. While recycling process water offers a sustainable path forward, accumulated species like metal ions, sulphates1, and natural organic materials2 fundamentally alter water properties and threaten flotation performance3–5.
This presentation delivers a comprehensive evaluation of how recycled and low-quality water influences the floatability of sulphide minerals (copper and molybdenum). From the lab-scale to full-scale operation, the underlying mechanisms using a dual approach were investigated: laboratory single-mineral flotation of chalcopyrite and molybdenite, and complex ore testing using process water sourced from real beneficiation plant in Peru. Utilizing surface-sensitive analytical techniques such as zeta potential and X-ray photoelectron spectroscopy (XPS), the physicochemical characterization was mapped driving the mineral-water-bubble interactions. The findings establish a predictive workflow for identifying how specific water-borne species impact positively or negatively metallurgical performance.

Keywords: process water, mineral flotation, recycled water, sulphides

References:

(1) Sinche-Gonzalez, M.; Fornasiero, D. Understanding the Effect of Sulphate in Mining-Process Water on Sulphide Flotation. Miner. Eng. 2021, 165, 106865. https://doi.org/10.1016/j.mineng.2021.106865.
(2) Sinche-Gonzalez, M.; Fornasiero, D.; Zanin, M. Flotation of Chalcopyrite and Molybdenite in the Presence of Organics in Water. Minerals 2016, 6 (4). https://doi.org/10.3390/min6040105.
(3) Schumann, R. , L. G. and D. R. Process Water Chemistry Influences in Base Metal Sulphides Flotation, Report to Newcrest Mining Ltd. ; Adelaide, 2002.
(4) Espinosa-Gomez, R.; Finch, J. A.; Laplante, A. R. Effects of the Type of Water on the Selective Flotation of Pyrochlore from Niobec. Colloids and Surfaces 1987, 26, 333–350. https://doi.org/10.1016/0166-6622(87)80125-7.
(5) Rao, S. R.; Espinosa-Gomez, R.; Finch, J. A.; Biss, R. Effects of Water Chemistry on the Flotation of Pyrochlore and Silicate Minerals. Miner. Eng. 1988, 1 (3), 189–202. https://doi.org/10.1016/0892-6875(88)90041-6.

Speaker: Dr Maria Sinche-Gonzalez (University of Oulu)

11:00 → 11:30 Perovskites: From Synthesis to Functional Properties

Over the last few decades, perovskite-type compounds (ABX₃) have attracted considerable scientific interest owing to their remarkable structural versatility and wide range of functional properties. Despite the apparent simplicity of the ideal perovskite crystal structure, this class of materials exhibits enormous compositional and structural flexibility, giving rise to a variety of intriguing physical and chemical properties. Consequently, they find applications in many fields, including catalysis, electrocatalysis, electronics, energy conversion and storage, sensing, and information technologies. Depending on their composition and structure, they may exhibit ferroelectricity, piezoelectricity, high-temperature superconductivity, colossal magnetoresistance, and many other technologically relevant properties. More recently, hybrid organic–inorganic perovskites have emerged as a new generation of semiconducting materials with outstanding performance in photovoltaic and optoelectronic applications.
The first part of this lecture will provide a general overview of the perovskite structure, major classes of perovskite materials, commonly used synthesis methods, and selected functional properties. The second part will focus on our research on complex inorganic perovskites synthesized by the solution combustion method using different fuels. Their crystal structures were refined by the Rietveld method using powder X-ray diffraction (PXRD) data, while various crystallographic parameters related to structural stability and distortion were calculated and analyzed. Structural, compositional, morphological, electrical, and electrocatalytic properties were systematically investigated using complementary characterization techniques. Particular attention was devoted to understanding how structural and microstructural factors influence the electrical conductivity and electrocatalytic performance of the synthesized materials, especially in reactions relevant to sustainable energy technologies, such as the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER).
The final part of the lecture will present selected results from our studies on bulk materials and thin films of hybrid organic–inorganic lead halide perovskites containing different organic cations. Their composition, crystal structure, morphology, optical properties, and electrochemical stability were investigated. Optical band-gap energies were determined from UV–Vis absorption spectra of the thin films using Tauc analysis, and the potential of these materials for photovoltaic applications was evaluated.

Keywords: perovskites, solution combustion synthesis, crystal structure, electrocatalysis, hybrid organic–inorganic perovskites, photovoltaic applications

Speaker: SLOBOTKA ALEKSOVSKA (University Ss Cyril and Methodius in Skopje, Faculty of Natural Sciences and Mathematics, Institute of Chemistry)

11:30 → 12:00 Industrial Waste as a Secondary Raw Material and Its Application in Accordance with the Circular Economy

The transition toward a circular economy requires the transformation of industrial waste streams into valuable secondary raw materials, reducing dependence on primary resources while minimizing environmental impacts associated with waste disposal. Among industrial by-products, coal fly ash represents one of the most significant residues generated from thermal power production and has considerable potential for resource recovery and sustainable material production.
This study aims to evaluate the potential of Macedonian coal fly ash as a secondary raw material through quantitative assessment and comprehensive chemical characterization, with particular emphasis on its suitability for the recovery of valuable elements and its further application within circular economy strategies. The estimated volume of fly ash generated from the investigated thermal power plant reaches 106.8 ± 5.1 million m³, indicating a significant secondary resource base. Chemical characterization revealed that the investigated fly ash samples are predominantly silicate-based materials, containing approximately 50 wt.% SiO₂, 19–20 wt.% Al₂O₃, and 15–16 wt.% Fe₂O₃, together with other alkali and alkaline earth metal oxides.
The assessment of potentially valuable and critical elements demonstrated the presence of significant concentrations of selected metals, including manganese (1100–5038 mg kg⁻¹), arsenic (31–191 mg kg⁻¹), gallium (30–35 mg kg⁻¹), as well as rare earth elements such as cerium (147–153 mg kg⁻¹) and lanthanum (60–78.1 mg kg⁻¹). These findings indicate that coal fly ash may represent a promising alternative source of valuable elements and contribute to the diversification of critical raw material supply chains. Furthermore, after the selective extraction of rare earth elements and other valuable metals, the remaining aluminosilicate-rich fraction retains significant potential for the synthesis of geopolymer materials, enabling a sequential valorization pathway and maximizing resource utilization.
These findings provide relevant information for researchers, industrial stakeholders, and potential investors interested in developing sustainable recovery and utilization technologies.

Speaker: Prof. Biljana Angjusheva (Faculty of Technology and Metallurgy, University "Ss Cyril and Methodius" in Skopje)