Determination of Dimethomorph,Cyazofamid and Its Metabolite Residue in Cucumber and Soil Using High Performance Liquid Chromatography-Tandem Mass Spectrometry
In order to evaluate the safety of dimethomorph and cyazofamid in cucumber and soil,a high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS) was developed for the simultaneous detection of dimethomorph,cyazofamid and its metabolite,4-chloro-5-p-tolylimidazole-2-carbonitrile(CCIM) in cucumber and soil.Samples were extracted with acetonitrile,cleaned up with PSA and C18,and then analyzed by HPLC-MS/MS in multiple reaction monitoring(MRM) mode with the matrix matched calibrations method.There existed good linearities for All analytes in the range of 0.01- 0.5 mg/L with their correlation coefficients(r) more than 0.994 0.At three spiked levels of 0.05,0.1 and 0.5 mg/kg,the recoveries for dimethomorph,cyazofamid and CCIM in cucumber and soil were in the range of 78%-105%with relative standard deviations(RSDs) of 1.3%-14.8%.The limit of quantitation was 0.05 mg/kg.Residues and dissipation of dimethomorph and cyazofamid in cucumber and soil were investigated.The half lives of dimethomorph in cucumber and soil were 1.2-2.1 d and 3.0-9.6 d,respectively,and the half lives of cyazofamid and CCIM in cucumber and soil were 0.9-2.3 d and 1.8-6.2 d,respectively.The method is simple,rapid,sensitive and accurate,and could meet the requirements for detection of dimethomorph,cyazofamid and CCIM residues in cucumber and soil.