Research on the Residue Dynamics of Avermectin in Cabbage and Soil with the Method of SPE-Pre-column Derivatization-HPLC

[Objective] An analytical method for the determination of avermectin residue in cabbage and soil was developed based on the pre-column derivatization-SPE-HPLC and the residue dynamics and final residue of avermectin in the cabbage and soil were studied.[Method] The sample of plant or soil was extracted with acetonitrile and purified by C18 solid-phase extraction(SPE) cartridge,then,constant volume with acetonitrile after its derivatization by N-methylimidazole(NMIM) and trifluoroacetic anhydride(TFAA),and finally,the content of avermectin residue was determined with RP-HPLC fluorescence detector(λex=365 nm and λem=475 nm).[Result] The results showed that the half-live of avermectin in cabbage and soil was 1.5-5.4 days and 6.7-8.8 days,respectively.Thus it was suggested that the suspension agent of 45.5% avermectin·diafenthiuron could be used for two times in the control of diamondback moth in cabbage of cruciferae and the safe interval period was 4 days.[Conclusion] The analytical method was simple,which result was met with the requirement of relevant standard in precision,accuracy and sensitivity.