SPE-柱前衍生-HPLC法研究阿维菌素在甘蓝及土壤中的残留动态

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

[目的]建立SPE-柱前衍生-HPLC法测定甘蓝和土壤中阿维菌素残留量的分析方法,并研究阿维菌素在甘蓝和土壤中的残留动态和最终残留量。[方法]样品用乙腈提取,C18固相萃取（SPE）小柱净化,经N-甲基咪唑（NMIM）和三氟乙酸酐（TFAA）衍生化,用乙腈定容,最后用液相色谱-荧光检测器（激发波长为365 nm,发射波长为475 nm）进行测定。[结果]阿维菌素在甘蓝中半衰期为1.5~5.4 d,在土壤中降解的半衰期为6.7~8.8 d。建议45.5%阿维菌素.丁醚脲悬浮剂防治十字花科蔬菜中的小菜蛾,在推荐剂量下最多施药2次,安全间隔期为4 d。[结论]建立的分析方法操作简单,方法的精密度、准确度和灵敏度都符合农药残留标准要求,适用于基质复杂的甘蓝和土壤中阿维菌素的残留测定。

[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.