Sample Preparation Approach by In Situ Formation of Supramolecular Solvent Microextraction for Enrichment of Neonicotinoid Insecticide Residues

An effective microextraction, namely, in situ formation of supramolecular solvent (SUPRAS) method, was investigated for the determination of neonicotinoid insecticides prior to high performance liquid chromatographic analysis. The microextraction method has been utilized for the first time in the literature for separation and preconcentration of neonicotinoid insecticides. The SUPRAS was rapidly in situ constructed by the inclusion of a colloidal 1-dodecanol suspension to tetrahydrofuran (THF) under salt (Na2SO4) addition for coacervation. The proposed microextraction method is grounded on electrostatic interaction between neonicotinoids and SUPRAS under salt persuaded phase separation. SUPRAS phase were separated after centrifugation, and then analysis by HPLC. The selected extraction condition were 100 mu L of 1-dodecanol, 1000 mu L of THF, 1.00 mg of Na2SO4, vortex for 15 s, and centrifugation at 3800 rpm for 4 min. Under the selected condition, the method contributed good linear range (0.010-1.00 mu g mL(-1)) with high coefficient of determination (R-2 > 0.99), high enrichment factor (33-fold for all analytes), and low limit of detection (0.010 mu g mL(-1)) for all analytes, which is lower than the maximum residue limit (MRL) established by EU. The RSD values of the retention times and peak areas range from 1.45 to 2.81% and 4.84 to 6.23%, respectively. The advanced method was desirably applied for the determination of the neonicotinoid insecticides in real samples including surface water, swimming pool water, and fruit juice samples. The acceptable percentage recoveries (81-119%) were gained.

Automated summary

An effective microextraction method, the in situ formation of supramolecular solvent (SUPRAS) method, was used to determine neonicotinoid insecticides prior to high performance liquid chromatographic analysis. This method showed good separation and preconcentration effects, and was successfully applied to real samples.