Research on the residue dynamics of avermectin in cabbage and soil with the method of SPE-Pre-column derivatization-HPLC | 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__

Chinese. ［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。

English. ［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.