Multi-residue analysis, dissipation behavior, and final residues of four insecticides in supervised eggplant field

In this study, the residues of four insecticides, spirotetramat, flonicamid, thiamethoxam, and tolfenpyrad, and their metabolites, including spirotetramat-enol, spirotetramat-mono-hydroxy, spirotetramat-keto-hydroxy, spirotetramat-enol-glucoside, 4-trifluoromethylnicotinamide, 4-trifluoromethylnicotinic acid, N-(4-trifluoromethylnicotinoyl) glycine, and clothianidin, were assessed using a single analysis method. The samples were extracted by acetonitrile, then purified by dispersive solid phase extraction and quantified using high performance liquid chromatography tandem mass spectrometry. The average recovery rate of 12 target compounds was 73.5-103.7%, the relative standard deviation was 1.1-18.3%, and the limit of quantification was 0.01-0.05 mg/kg. The results showed good linearity (R² >0.99), meeting the requirements of the pesticide residue analysis. The dissipation half-lives of the four insecticides in eggplant were 3.4-14.5 days. After the last applications at 7 and 10 days, the final residues of the four insecticides in eggplant were <0.01-0.21, 0.085-0.26, <0.05-0.078, and <0.01-0.21 mg/kg, respectively. The dissipation and final residue results could provide a theoretical basis for the rational application of four insecticides in eggplant fields.HighlightsHPLC-MS/MS for simultaneous determination of four insecticides and their metabolites in eggplant fields.The dissipation dynamics and final residue of the target compounds in field eggplant were studied.Guidance for the safe use of four insecticides on eggplant.