Determination of eight neonicotinoid insecticides in Chinese cabbage using a modified QuEChERS method combined with ultra performance liquid chromatography-tandem mass spectrometry

A modified QuEChERS method was developed and combined with ultra performance liquid chromatography-tandem mass spectrometry to analyze eight neonicotinoid insecticides in Chinese cabbage. Herein, acetonitrile served as extraction solvent. Anhydrous sodium sulfate replaced the traditional anhydrous magnesium sulfate in the phase partition process to eliminate the influence of salt caking and heat release. Primary secondary amine and graphitized carbon black were selected as dispersive-solid phase extraction sorbents according to the clean-up efficiency evaluated by post-column infusion. The method showed good sensitivity with the limits of quantification below 1.0 μg/kg for eight analytes. The average recoveries ranged from 79.0% to 108.4% for three fortification levels, and the matrix effect could be ignored. For the tested samples, six neonicotinoids were detected, while cycloxaprid and imidaclothiz were not. The developed analytical method provided a powerful tool for monitoring neonicotinoid insecticides residues in Chinese cabbage.