气相色谱-质谱法测定涉案奶粉中辛硫磷的含量

Determination of Phoxim in Milk Powder by Gas Chromatography-Mass Spectrometry

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。

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.