气相色谱-三重四极杆质谱测定中老年奶粉中甲基硒代半胱氨酸

采用气相色谱-三重四极杆质谱联用仪对中老年奶粉中的甲基硒代半胱氨酸进行定性确证和定量分析。样品经三氯乙酸和乙腈提取后,用氯甲酸乙酯在乙醇吡啶介质中衍生,衍生物经HP-5MS色谱柱分离并使用多反应监测模式进行定性和定量分析。甲基硒代半胱氨酸的线性范围为0.005～1.0 mg/L,方法检出限和定量下限分别为0.01、0.05 mg/kg。奶粉样品在0.05、0.2、0.4 mg/kg 3个加标水平下的平均回收率为79%～86%,相对标准偏差为2.8%～4.0%。该方法能满足中老年奶粉中甲基硒代半胱氨酸的质量控制需要。

Determination of Methyl Selenocysteine in Middle-aged Milk Powder by Gas Chromatography-Triple Quadrupole Mass Spectrometry

A gas chromatography-triple quadrupole mass spectrometric method was developed and validated for the determination of methyl selenocysteine in middle-aged milk powder.The analytes were extracted with trichloroacetic acid and acetonitrile,and derived with ethyl chloroformate in ethanol-pyridine.Methyl selenocysteine was separated on an HP-5MS micro-column,and quantified under multiple reaction monitoring mode.The calibration curve was linear in the range of 0.005-1.0 mg/L,with detection limit of 0.01 mg/kg and quantitation limit of 0.05 mg/kg.The average recoveries of methyl selenocysteine from middle-aged milk matrixes at the spiked level of 0.05,0.2,0.4 mg/kg ranged from 79% to 86% with relative standard deviations of 2.8%-4.0%.The method could meet the requirement for determination of methyl selenocysteine in middle-aged milk powder.