Synthesis and characterization of phosphocholine chloride-based three-component deep eutectic solvent: application in dispersive liquid-liquid microextraction for determination of organothiophosphate pesticides.

A new type of deep eutectic solvent based on three components using phosphate salts has been synthesized, characterized, and applied in the extraction of eight organothiophosphate pesticides from honey samples. In this study, the deep eutectic solvent was prepared from phosphocholine choline chloride as a hydrogen bond acceptor and dichloroacetic acid and decanoic acid as hydrogen bond donors. The method consisted of two steps in which initially the analytes were extracted from the samples into a water-miscible organic solvent. In the second step, the extracted phase was mixed with the prepared deep eutectic solvent and the mixture was used in the following dispersive liquid-liquid microextraction method. The method was validated under optimal conditions, and it was found that it has low limits of detection (0.05-0.10 ng g-1 ) and quantification (0.19-0.36 ng g-1 ), good linearity (r2  ≥ 0.994), broad linearity (0.36-1000 ng g-1 ), and satisfactory repeatability (relative standard deviation ≤10% for intra- (n = 6) and inter-day (n = 4) precisions at a concentration of 2 ng g-1 of each analyte). The proposed method was applied in different honey samples, and malathion was found at a concentration of 29 ng g-1 in one sample. © 2019 Society of Chemical Industry.