Combining modified graphene oxide-based dispersive micro solid phase extraction with dispersive liquid–liquid microextraction in the extraction of some pesticides from zucchini samples

Abstract

By industrialization of agriculture and increasing the use of pesticides to preserve agricultural products, there is a growing attention to introduce new analysis approaches for the determination of pesticides residues in vegetables. To reach this goal, an efficient dispersive micro solid phase extraction method combined with dispersive liquid–liquid microextraction was used during extraction of eight pesticides (chlorpyrifos, diazinon, tebuconazole, deltamethrin, permethrin, haloxyfop-methyl, penconazole, and cyhalothrin) from zucchini samples previous to their determination by gas chromatography. The studied pesticides were initially transferred from zucchini into a solution and then they are extracted by the adsorption method in which the graphene oxide particles modified by a deep eutectic solvent were applied as a new sorbent. In the following, the analytes were more concentrated by the microextraction technique. The presented method was validated and low limits of detection (1.0–1.8 ng g−1) and broad linear ranges for the calibration graphs (5.8–1000 ng g−1) with satisfactory coefficients of determination (r2 ≥ 0.994) were obtained. By performing the introduced method on zucchini samples, tebuconazole was found and determined in one of them.