提出了气相色谱-串联质谱法测定稻米中毒死蜱及其代谢物3,5,6-三氯-2-羟基吡啶(TCP)含量的方法。样品经含体积分数为1%盐酸的乙腈提取,盐析并浓缩至近干后,残渣用乙酸乙酯溶解TCP用N-甲基-N-叔丁基二甲基硅基三氟乙酰胺衍生化,用气相色谱-串联质谱法测定,外标法定量。毒死蜱及TCP的质量浓度与峰面积均在0.02~0.4 mg·L-1范围呈线性关系,测定下限(10S/N)依次为0.5,0.2 μg·kg-1。在3个浓度水平下进行了回收和精密度试验,毒死蜱和TCP的回收率分别在94.3%~111.9%和95.1%~109.6%范围内,相对标准偏差(n=5)分别在1.7%~4.0%和3.1%~11.6%范围内。

GC-MS/MS was applied to the determination of chlorpyrifos and its metabolite 3,5,6-trichloro-2-hydroxy pyridine (TCP) in rice. Samples were extracted with acetonitrile which contained (φ) 1% HCl. The extract was treated by salting out and evaporated to near-dryness and the residue and dissolved with ethyl acetate. TCP was derivatized with N-methyl-N-tert-butyl trimethylsilyl trifluoroacetamide, and the derivatized product and chlorpyrifos were determined by GC-MS/MS. External standard calibration was adopted in the determination. Linear relationships between peak areas and mass concentrations of chlorpyrifos and TCP were obtained in the same range of 0.02-0.4 mg·L-1. Values of lower limit of determination (10S/N)were 0.5 μg·kg-1 for chlorpyrifos and 0.2 μg·kg-1 for TCP. Tests for recovery and precision were made by standard addition method at 3 different concentration levels, values of recovery found were in the ranges of 94.3%-111.9% and 95.1%-109.6% with values of RSD′s (n=5) in the ranges of 1.7%-4.0% and 3.1%-11.6% for chlorpyrifos and TCP respectively.