GC-MS测定牛奶中有机磷残留的不确定度评定研究

目的 采用气相色谱法-质谱法对牛奶中有机磷农药残留的不确定度进行评估。方法 通过气质联用法对测定牛奶中有机磷农药残留量测定过程进行分析，应用数学模型计算出测定过程中的不确定度，最后计算出相对合成标准不确定度和扩展不确定度。结果 当牛奶中敌敌畏含量为0.507 mg/kg时，其扩展不确定度为7.35×10-3 mg/kg(k=2)；当牛奶中甲拌磷含量为0.509 mg/kg时，其扩展不确定度为5.45×10-3 mg/kg(k=2)；当牛奶中乐果含量为0.450 mg/kg时，其扩展不确定度为6.35×10-3 mg/kg (k=2)；当牛奶中毒死蜱含量为0.459 mg/kg时，其扩展不确定度为6.09×10-3 mg/kg (k=2)；当牛奶中对硫磷含量为0.435 mg/kg时，其扩展不确定度为6.53×10-3 mg/kg (k=2)。结论 影响测量结果不确定度的主要来源为测量重复性和方法的准确度，其他因素的影响相对较小。

Uncertainty Evaluation of Organic Phosphorus Residues in milk Determination by GC-MS

To evaluate organic phosphorus residues in milk by gas chromatography tandem mass spectrometry. Methods the evaluation process of organic phosphorus residues in milk was determined by gas chromatography tandem mass spectrometry (GC-MS), at the same time, mathematical model was applied to calculate the uncertainty component in the process, then, the relative combined standard uncertainty and expanded uncertainty were calculated. Results The expanded uncertainty was 7.35×10-3, 5.45×10-3, 6.35×10-3, 6.09×10-3 and 6.53×10-3 mg/kg (k=2), when dichlorvos, phorate, dimethoate, chlorpyrifos and parathion content in milk was 0.507, 0.509, 0.450, 0.459 and 0.435 mg/kg, respectively. Conclusion The main sources which affect the uncertainty measurement were the repeatability of measurement and accuracy of method, other factors had less affect to uncertainty measurement.