Abstract: Objective To establish a method for determining the content of phoxim in milk powder by gas chromatography-mass spectrometry（GC-MS）. Methods The samples were extracted with ethyl acetate and purified by Florisil solid-phase extraction column. The eluent was analyzed by GC-MS. Results It had good linear relationship in the range of 0.10-5.00 mg/L. The limit of detection was 0.05 mg/L. The spiked recoveries of phoxim in milk powder ranged between 98.2 %~101 %. The relative standard deviation （RSD） ranged from 2.1 % to 3.1 %. The analyte detected in case samples had the same retention time with phoxim at about 8.377 min. The qualitative ions （base peak m/z 109, m/z 135, m/z 298） were in accordance with those of phoxim. The content of phoxim in the questioned sample was determined as 2.17 mg/kg. Conclusion The established method is simple, sensitive and feasible. It can be used for the determination of phoxim in milk powder, and provide useful reference for the determination of other phoxims.

Key words: forensic toxicology, gas chromatography-mass spectrometry （GC-MS）, phoxim, milk powder

摘要： 目的 建立基于气相色谱-质谱法（GC-MS）测定奶粉中辛硫磷含量的方法。方法 对待测样品进行乙酸乙酯萃取，利用Florisil固相萃取柱净化，淋洗液供GC-MS分析，设置适当的色谱质谱条件分析检测。结果 该方法在0.10~5.00 mg/L内具有良好的线性关系，辛硫磷在奶粉中的最低检出限为0.05 mg/L，加标回收实验结果表明，辛硫磷在奶粉中的平均回收率为98.2 %~101 %，相对标准偏差为2.1 %~3.1 %。案件检材样品在保留时间约8.377 min处出现与辛硫磷标准品相似色谱峰，且质谱定性离子[m/z 109（基峰）、m/z 135、m/z 298]与辛硫磷标准溶液一致，辛硫磷的含量为2.17 mg/kg。结论 该方法操作简单、灵敏度高、可行性强，可用于检测奶粉中的辛硫磷成分，为其他辛硫磷检测提供有益借鉴。

关键词: 法医毒物学, 气相色谱-质谱法, 辛硫磷, 奶粉