毒死蜱、吡虫啉、螺虫乙酯及其代谢物和苯醚甲环唑在梨中的残留消解动态

利用仪器分析方法和田间试验法，研究了毒死蜱、吡虫啉、螺虫乙酯及其代谢物和苯醚甲环唑在梨中的残留消解动态。样品经乙腈提取，氯化钠盐析净化，毒死蜱采用气相色谱-质谱联用仪检测，其他3种农药采用液相色谱-质谱联用仪检测，外标法定量。结果表明:毒死蜱、吡虫啉、螺虫乙酯及其代谢物和苯醚甲环唑4种农药在梨中的消解动态均满足一级反应动力学方程，半衰期分别为4.4、12.2、13.1和10.3 d。施药后7 d至收获期，4种农药在梨中的最终残留量均未超出中国国家标准中规定的最大残留限量值，按照推荐剂量及其操作规范在梨上施用是安全的。

Residues and dissipation dynamics of chlorpyrifos, imidacloprid, spirotetramat and its motablites, difenoconazole in pear

The instrument anlysis method and field testing method were employed for the investigation 3 of the dissipation dynamics and residues of chlorpyrifos, imidacloprid,spirotetramat and its motablites, difenoconazole, in pear. The samples were extracted with acetonitrile and purified by sodium chloride salting out. Chlorpyrifos was detected by GC/MS/MS, and the other three pesticides were detected by LC/MS/MS. Quantization was performed using external standard method. The results showed that the dissipation dynamics of chlorpyrifos, imidacloprid, spirotetramat and its motablites, difenoconazole, in pear meet the first-degree dynamics matrix. There half-lives were 4.4, 12.2, 13.1 and 10.3 d, respectively. From 7 days after the pesticide application to harvest, the final residues of the above 4 pesticides in pear did not exceed the MRL value of China. According to the recommended application concentration and operating procedures, All four pesticides can be safely used on pears.