A natural deep eutectic solvent‑based liquid‑liquid microextraction for the determination of bisphenols in mineral and river water samples

This study aims to develop a novel method for the determination of five bisphenols (specifically BPS, BPA, BPAP, BPAF, and BPF) in aqueous samples using a natural deep eutectic solvent (NADES) as extractant phase. The environmentally friendly extractant decanoic acid:DL-menthol (1:2 M ratio) has been employed for the extraction and preconcentration of BPs using dispersive liquid-liquid microextraction prior to liquid chromatography coupled with a diode array detector. The methodology has been evaluated under optimized extraction conditions, namely NADES volume (50 μL), sample pH (7), extraction time (3 min), centrifugation speed (370 g-force) and centrifugation time (1 min), resulting in good linearity with correlation coefficients between 0.993 and 0.999. The relative standard deviation was found to range from 4 to 19 %, while the detection limits were established between 1.5 and 3.3 μg/L. In the course of evaluating the recovery on different water samples, including mineral water, river water, and water from an organization engaged in the direct supply of packaged drinking water to end consumers, the relative recovery values ranged between 70 and 119 %. Additionally, a migration study was conducted utilizing polycarbonate bottles. Finally, an evaluation of the method environmental impact was performed with AGREEprep metric, providing the highest value compared to previous methodologies for the same purpose.