气相色谱-质谱法测定食品中甲基汞的含量

Determination of methylmercury content in food by gas chromatography- mass spectrometry

中文关键词:  甲基汞  食品  气相色谱-质谱法

英文关键词:methylmercury  food  gas chromatography-mass spectrometry

中文摘要:

      目的 建立气相色谱-质谱法(gas chromatography-mass spectrometry, GC-MS)测定食品中的甲基汞含量。方法 样品经氯化钠盐析和甲苯萃取, 经L-半胱氨酸水溶液反向萃取后采用四苯硼钠衍生, 经Rxi-5MS毛细管色谱柱分离; 质谱采用电子轰击源离子化, 以选择离子扫描方式对样品中的甲基汞含量进行质谱分析。结果 甲基汞在0.05~1 μg/mL线性范围内具有良好的线性关系, 相关系数为0.9998, 检出限为10 μg/kg。当甲基汞加标水平为0.2、0.5和1.0 mg/kg时, 方法平均回收率为81.5%~95.2%, 相对标准偏差为1.0%~2.3%(n=6)。结论 该方法降低了甲基汞的活性, 减少甲基汞在色谱柱上的吸附和峰拖尾的现象, 具有操作简便快速、灵敏度高等优点, 可适用于食品中甲基汞含量的测定。

英文摘要:

      Objective To establish a method for determination of methylmercury in food by gas chromatography- mass spectrometry (GC-MS). Methods Samples were processed with the sodium chloride salting-out, extracted with methylbenzene, and the extracted solution was processed with reverse extraction with L-cysteine aqueous solution and then derived with sodium tetraphenylborate. The derivatives were separated by a Rxi-5MS column. Mass spectrometry used electron-impact ion source (EI) for ionization and selected ion monitoring (SIM) mode for analysis of methylmercury content in food. Results Methylmercury had a good linear relationship in the range of 0.05~1 μg/mL, with the correlation coefficient of 0.9998, and the detection limit was 10 μg/kg. The average recoveries spiked at 3 levels of 0.2, 0.5 and 1.0 mg/kg were 81.5%~95.2% with the relative standard deviation of 1.0%~2.3% (n=6). Conclusion The established method can decrease the activity of methylmercury, and reduce the absorption of methylmercury and peak tailing in chromatographic column, which is suitable for determination of methylmercury in food due to its advantages of simple and rapid operation and high sensitivity etc.