Abstract: In this study, a method for the determination of residues of four new neonicotinoid insecticides (thiamethoxam, imidacloprid, acetamiprid, and thiacloprid) in edible oil was developed using ultrasound-assisted liquid-liquid microextraction with deep eutectic solvent (UA-DES-LLME) followed by high performance liquid chromatography (HPLC). Samples were diluted with n-hexane and added with deep eutectic solvent (DES) before being subjected to ultrasonic-assisted dispersive liquid-liquid microextraction (UALLME). Then, the extract was centrifuged. The lower DES-rich phase was collected and injected into the HPLC system for analysis. Several important parameters influencing the extraction efficiency, such as the type and volume of DES, ultrasonication time, and centrifugation time, were investigated. Under the optimized conditions, the recoveries of the analytes were between 81.9% and 98.0%, with relative standard deviations (RSD, n = 5) of 5.5%–8.3%. The limits of detection (LODs) and limits of quantitation (LOQs) were 3.2?5.3 μg/L and 10.8?17.7 μg/L respectively. The method was successfully applied to real samples of soybean oil, sunflower seed oil and linseed oil. This method combined extraction and concentration in one step without the use of poisonous organic solvents. This method proved to be simple, rapid and efficient.

Key words: deep eutectic solvent; liquid-liquid microextraction; new neonicotinoid insecticides; edible oil