Speaker
Description
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”.