Residue and dissipation dynamics of tolfenpyrad in radish
[Aims]A high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS)method for the determination of tolfenpyrad residues in radish and soil was established to study the dissipation dynamics of tolfenpyrad in radish plants,succulent roots and soil.[Methods]The samples were extracted with acetonitrile,purified by PSA,GCB and anhydrous MgSO4,quantified by external standard method,and detected by HPLC-MS/MS.[Results]The linear relationship of tolfenpyrad in radish plant,succulent root and soil samples was good in the range of 0.001-1 mg/L(R2＞0.999).At the spiked levels of 0.01,0.1,0.5 and 10 mg/kg,the average recoveries of tolfenpyrad in radish plants were 101.8％-105.2％,with the relative standard deviations of 1.6％-5.5％.At the spiked levels of 0.01,0.1 and 0.5 mg/kg,the average recoveries of tolfenpyrad in radish succulent root and soil were 94.2％-97.8％and 95.1％-98.7％,respectively.The relative standard deviations(RSDs)were 0.9％-3.8％and 1.3％-2.2％,respectively.The half-lives of tolfenpyrad in radish plants and soil were 2.5-9.8 and 5.4-13.6 d,respectively.The final residues of tolfenpyrad in radish plants,radish succulent roots and soil were 0.010-4.366,＜0.01-0.092 and＜0.01-0.170 mg/kg,respectively.[Conclusions]The method is simple,accurate,sensitive and reproducible,and meets the requirements for the detection and analysis of tolfenpyrad residues in radish.The dissipation dynamics and final residue test provide data support for evaluating the rational use of tolfenpyrad in radish and the formulation of maximum residue limit.It is safe to apply chlorfenapyr·tolfenpyrad 20％SC at the recommended dose during the harvest interval.This study can provide a reference for the safe use of tolfenpyrad and the formulation of maximum residue limit(MRL).
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