Dispersive liquid–liquid microextraction based on deep eutectic solvent followed by high-performance liquid chromatography-ultraviolet for imidacloprid, hexythiazox, and fenpyroximate determination: Experimental design approach

Abstract

Dispersive liquid–liquid microextraction (DLLME) of three insecticides, including imidacloprid (I), hexythiazox (H), and fenpyroximate (F), was performed as an efficient method for separation and preconcentration using a deep eutectic choline chloride-acetic acid solvent (DES) followed by determination by high-performance liquid chromatography-ultraviolet (HPLC-UV). The experimental design approach (central composite design) was used to optimize the effective parameters. According to the results, the addition of salt had no significant effect on extraction among the four parameters studied, including pH, DES volume (dispersive solvent), salt concentration, and chloroform volume. The optimized conditions in the DES-DLLME-HPLC-UV method were pH = 6.00, 100 µL DES, and 138 µL chloroform. Under optimized conditions, a wide linear range of 1.00 × 10−3-20.00 µg mL−1 was obtained for three insecticides. The enhancement factors were 11.22, 58.04, and 39.65 and the limit of detection of 3.00 × 10−4, 2.00 × 10−4, and 2.00 × 10−4 µg mL−1, and the limit of quantification of 9.00 × 10−4, 8.00 × 10−4, and 6.00 × 10−4 µg mL−1 were also determined for imidacloprid, hexythiazox, and fenpyroximate, respectively. The presence of other components including benomyl, dimethoate, mancozeb, captan, thiodicarb, carbendazim, and oxyfluorfen, showed no significant interference effect on the determination of three insecticides up to 50-fold. The method is eco-friendly benign, sensitive, precise, and straightforward as shown by the results.