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Natural deep eutectic solvents (NADES) are emerging as eco-friendly alternatives to conventional solvents, offering higher extraction efficiency and lower environmental impact. This study investigated the potential of nineteen NADES, synthesized from choline chloride in combination with organic acids, carbohydrates, urea, and glycerol, for the extraction of phenolic acids.
The solvents were characterized by FT-IR and evaluated for key physicochemical properties. They exhibited higher densities (1.13–1.40 g/mL) and surface tensions (35–88 mN/m) than water. Conductivity (36.1–8460 μS/cm), adjustable pH (1–9), and elevated refractive indices (1.42–1.54) indicated high polarity, tunability, and strong solute–solvent interactions favorable for phenolic acid extraction.
Twenty phenolic acids, including coumaric, caffeic, ferulic, and their derivatives, were successfully extracted. Organic acid–based NADES demonstrated the highest extraction efficiency, followed by carbohydrate-based systems, whereas urea- and glycerol-based NADES were less effective. Among them, choline chloride–organic acid systems, particularly choline chloride–oxalic acid (1:1) and choline chloride–tartaric acid (2:1), achieved the best performance.
These findings highlight the importance of careful hydrogen bond donor/acceptor selection for tailoring NADES properties and optimizing phenolic acid extraction. Future studies should focus on fine-tuning NADES composition to target specific analytes and further improve extraction efficiency.
Keywords: NADES, extraction effectiveness, phenolic acids, pH
Acknowledgement: This work has been supported by Macedonian Ecological Society for the financial support of the project titled “An ecological approach for the extraction of bioactive compounds from Hypericum perforatum using deep eutectic solvents”.
