Multi-response optimization of a deep eutectic solvent‑based microextraction method for the simultaneous extraction of twenty organochlorine pesticides for monitoring in various water samples

Abstract

This study investigates the application of a relatively hydrophobic deep eutectic solvent (DES) for ultrasound-assisted emulsification-microextraction of twenty organochlorine pesticides from environmental water samples before determination by gas chromatography equipped with a micro-electron capture detection. To find the highest global extraction efficiency, the central composite design combined with the desirability function (DF) approach was utilized for multi-response optimization of effective parameters, including DES volume, pH, salt concentration, and sonication time. DES was prepared by combining choline chloride as a hydrogen bond acceptor and 1-phenylethanol as a hydrogen bond donor in a mole ratio 1:4. The optimum conditions corresponding to 0.888 in the DF were pH 10.10, DES volume of 73 µL, salt concentration of 17.44% (w/v), and sonication time of 7.36 min. The analytical performance of the method was evaluated under optimum conditions and a wide linear range (0.05–30 ng/mL) with good linearity (R2 > 0.9967), low limit of detection (3.5–33 pg/mL), high enrichment factors (151.1–616.3), and good extraction recoveries (27.2–98.6%) were obtained. The potential of using the method to determine OCPs in four real water samples was proved through high relative recoveries values. The Green Analytical Procedure Index (GAPI) tool was used to evaluate the method's greenness, which confirms the superior eco-friendship of the method compared to other methods.