Cloud-point extraction coupled to in-situ metathesis reaction of deep eutectic solvents for preconcentration and liquid chromatographic analysis of neonicotinoid insecticide residues in water, soil and urine samples

A simple cloud-point extraction coupled to in-situ metathesis reaction of deep eutectic solvents method followed by high-performance liquid chromatography for rapid determination of neonicotinoid insecticide residues (i.e. thiamethoxam, clothianidin, imidacloprid, and thiacloprid) was developed. The method is based on the use of deep eutectic solvents (choline chloride - phenol) as disperser solvent and Triton X-114 as extraction solvent. Various experimental parameters affecting the extraction efficiency such as salts addition, types and concentrations of surfactant, concentrations of hydrogen bond donor and hydrogen bond acceptor were investigated and optimized. Four neonicotinoid insecticides were separated within 9 min using monolithic column, with a mobile phase of 26% (v/v) acetonitrile in water, at a flow rate of 1.0 mL min(-1) , and photodiode array detection at 254 nm. Under the optimum conditions, wide linear range (1-1000 mu g L-1), high enrichment factors (EF) (50-250) and low limits of detection (0.3-1.0 mu g L-1) were obtained. The proposed method was successfully applied to determine neonicotinoid insecticide residues in surface water, soil and urine samples and high recoveries (80-115%) were obtained.