Determination and dissipation of flucarbazone-sodium and its metabolite in wheat and soils by LC-MS/MS

Abstract

Study on the determination and dissipation of the pesticide and its relevant metabolite in commodity and environmental samples is an important task to evaluate their formation, stability, and toxicity. In this work, a rapid analytical method based on the extraction with a mixture of acetonitrile/water and cleanup with graphite carbon black was developed for the analysis of flucarbazone-sodium and its metabolite, (2-(trifluoromethoxy) benzene sulfonamide). The determination of both of the compounds in wheat and soil samples was performed using liquid chromatography–tandem quadrupole mass spectrometry. The average recoveries ranged from 87.0% to 99.6% for flucarbazone-sodium and 83.2% to 102.8% for the metabolite in wheat plant, straw, grain, and soil samples. Relative standard deviations for the two compounds were in the range of 1.5–8.7% for all of the matrices. Real wheat and soil samples were analysed to investigate the dissipation and transfer of the two analytes in wheat and soils under field conditions. The results showed the dissipation rates of flucarbazone-sodium fit to first-order kinetics and its half-lives ranged from 1.5 to 3 days in wheat plants and from 8 to 14 days in soils. By contrast, the residues of the metabolite in wheat plants decreased after the application, whereas the residue concentrations increased gradually with the sampling occasions in soil samples. At harvest time, no flucarbazone-sodium or its metabolite was detected in any of the wheat or soil samples. This work would be helpful for setting maximum residue limits of flucarbazone-sodium including 2-(trifluoromethoxy) benzene sulfonamide in wheat and revealing the conversion of the two compounds in soils in China.