Residue and dissipation of amisulbrom in tobacco leaves by liquid chromatography-tandem mass spectrometry

To study the residue and dissipation of amisulbrom in tobacco of crop field trials, a QuEChERS method combined with LC-MS/MS was developed. Samples were extracted with acetonitrile, cleaned up by primary secondary amine, and detected by LC-MS/MS with quantification by external standard method. It was showed that the average recoveries of amisulbrom were 88%-93% and 93%-107% with relative standard deviations of 2.5%-13.9% and 6.7%-7.4% in fresh and cured tobacco leaves, respectively. The limits of quantification were 0.01 mg/kg and 0.02 mg/kg for fresh and cured tobacco leaves, respectively. The dissipation and final residues of amisulbrom in tobacco were determined in Shandong and Sichuan, China during 2013 to 2014. The dissipation results showed the half-lives of amisulbrom in fresh tobacco leaves were 5.1-9.8 days. The final residues of amisulbrom in cured tobacco leaves were determined after three or four applications at 105 g a.i./hm2 and 157.5 g a.i./hm2. The final residues of amisulbrom were all in the range of below LOQ to 5.95 mg/kg 14 days after the last application in cured tobacco leaves.