Determination of sulfoxaflor residues in vegetables, fruits and soil using ultra-performance liquid chromatography/tandem mass spectrometry

Sulfoxaflor is a novel sulfoximine insecticide which is effective against a wide range of sap-feeding insect pests, including aphids, whiteflies, hoppers, and lygus. In this study, a rapid, highly sensitive and selective method was developed for determining sulfoxaflor residues in vegetables, fruits and soil by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The target compound was extracted with acetonitrile and cleaned with dispersive solid phase extraction using primary and secondary amine (PSA). Two pairs of precursor product ion transitions for sulfoxaflor were measured and evaluated. Satisfactory linearities in the range of 10-1000 mu g L-1 of sulfoxaflor were obtained, where the correlation coefficients (R-2) were higher than 0.9977 in all cases. Average recoveries in cucumber, tomato, cabbage, apple, grape and soil at three levels (10 mu g kg(-1), 100 mu g kg(-1) and 1000 mu g kg(-1)) ranged from 78.4% to 98.7%, with relative standard deviations (RSDr) from 1.2% to 14.5%. The reproducibility (RSDR) ranged from 2.9 to 15.6%. The LODs ranged from 0.2 to 0.6 mu g kg(-1), and LOQs from 0.7 to 2.0 mu g kg(-1). This method was used to determine sulfoxaflor residues in cucumber and soil samples for studies of their dissipation under field conditions. The trial results showed that the half-lives of sulfoxaflor obtained after treatment ranged from 1.6 to 2.9 days in cucumber and from 1.5 to 7.2 days in soil in Shandong, Henan and Zhejiang. The developed analytical method provides a basis to establish maximum residue limits and monitor sulfoxaflor residues in vegetables and fruits.