Degradation Dynamics and Residue Analysis of Flubendiamide in Cabbage and Soil by Liquid Chromatography-Tandem Mass Spectrometry with Dispersive Solid Phase Extraction

Abstract

To formulate a scientific basis for a reasonable spray dose and safe interval period of 20% fluben-diamide water dispersible granule (WDG) on controlling vegetable pests, degradation dynamics of flubendiamide in cabbage and soil was analyzed in this study. Dissipation and residue of fluben-diamide in 20% flubendiamide WDG in cabbage and soil under field conditions were investigated by liquid chromatography-tandem mass spectrometry with dispersive solid phase extraction. Re-sults showed that the degradation dynamic equations of flubendiamide in cabbage and soil were based on the first-order reaction dynamic equations. The half-lives of the degradation of fluben-diamide were 3.51 d to 3.96 d and 3.43 d to 3.87 d in the cabbage of Yangzhou and Jingzhou, re-spectively, and 4.42 d to 5.13 d and 4.37 d to 4.99 d in the soil of Yangzhou and Jingzhou, respec-tively. The terminal residues of flubendiamide in the cabbage of Yangzhou and Jingzhou were 0.0247 mg • kg −1 to 0.0393 mg • kg −1 and 0.0225 mg • kg −1 to 0.0273 mg • kg −1 , respectively, when 20% flubendiamide WDG was applied at a dose of 0.050 g • m −2 . Flubendiamide is safe to be applied in cabbage fields at the recommended dose.