嘧菌酯和百菌清在甘蓝中的残留及消解动态OA

To evaluate the safety of 560 g·L-1 azoxystrobin·chlorothalonil suspension concentrate on cabbage,the residues and dissipation dynamics of azoxystrobin and chlorothalonil in cabbage were determined by QuEChERS-HPLC-MS/MS and QuEChERS-GC,respectively,at different application concentrations(recommended dose and 2 times the recommended dose).The results showed that the dissipation of azoxystrobin and chlorothalonil residues in cabbage conformed to the first-order kinetic model at the two application concentrations.Although the pesticide residues increased significantly and the dissipation rate decreased at 2 times the recommended dose,the half-lives were all less than 6 days,indicating that they were easily degradable pesticides.The residue's level of azoxystrobin in cabbage were all less than 5 mg·kg-1(MRL)at the two application concentrations,and the dissipation rate was more than 88%after 14 days of application.However,the residue level of chlorothalonil at 2 times the recommended dose was still higher than the MRL value after 14 days of application and did not meet the standard.Therefore,it is recommended that 560 g·L-1 azoxystrobin·chlorothalonil suspension concentrate be applied strictly at the recommended dose in open-field cabbage cultivation,and a harvest interval of 14 days or more should be observed.