Hydrophobic natural deep eutectic solvent-based DLLME for the green HPLC determination of paraben and alcohol preservatives in water samples

A simple, rapid, and environmentally friendly dispersive liquid-liquid microextraction (DLLME) method using hydrophobic natural deep eutectic solvents (NADES) was developed for the simultaneous determination of six parabens and phenoxyethanol in water samples. The extraction performance of several NADES composed of thymol, menthol, and fatty acids was evaluated, selecting a thymol: decanoic acid system (2:1 molar ratio) as the optimal extractant. Critical experimental variables were optimized using a multivariate approach combining Plackett-Burman and central composite designs. Under optimal conditions, the method provided high enrichment factors (85 - 133), good precision (RSD < 13%), and limits of detection between 0.065 and 0.56 ng mL -1 . The method was applied to analyze different water samples, including tap, river, and wastewater samples obtaining recoveries between 78% and 118% for all the analytes in the spiked samples. The greenness and practicability of the developed method were evaluated using ChlorTox, AGREE, AGREEprep, and BAGI metrics, confirming the reduced environmental impact of the proposed approach, mainly due to the use of bio-based solvents and miniaturized extraction procedure. This method represents a sustainable and efficient alternative for monitoring emerging preservatives in environmental waters.