ICP-MS法和HPLC-HG-AFS法测定婴幼儿配方奶粉中硒质量浓度不确定度的比较

Comparative study of uncertainty evaluation for the determination of selenium content in infant formula milk powder by ICP-MS and high performance liquid chromatography with atomic fluorescence spectromeytry

采用电感耦合等离子体质谱法(ICP-MS)和高效液相色谱-氢化物-原子荧光光谱法(HPLC-HG-AFS)分别测定婴幼儿配方奶粉中硒的质量浓度。比较全面地考虑了整个测定过程的不确定度来源,对影响结果不确定度的各个因素作了系统分析,建立了结果不确定度评估数学模型,探讨了其测定结果不确定度,并对评估结果进行比较。分析不确定度的来源主要包括样品前处理过程、测量过程中的随机效应(测量重复性)、性标准工作曲线拟合及测量仪器等引入的不确定度分量。通过合成得到测量结果的合成不确定度,扩展不确定度及测试结果的报告形式。结果表明:ICP-MS法和HPLC-HG-AFS法扩展不确定度(UI)(k=2)为0.016 mg/kg和0.024 mg/kg。

The content of selenium in infant formula milk powder was determined by inductively coupled plasma-mass spectrometry （ICP-MS） and liquid chromatography with atomic fluorescence spectrometry, respectively. The sources of uncertainty in the measurement process were comprehensively considered. The various factors that affect the uncertainty were systematically analyzed. A mathematical model for uncertainty evaluation was established and used to comparatively evaluate the uncertainties of the two analytical methods. The major un- certainty sources were sample pretreatment,tandard curve fitting, measurement repeatability and performance of the instruments. The expand- ed uncertainty of the two methods was obtained respe ctively by calculating each variable uncertainty and combined uncertainty. The results sho wed that two methods were 0.020 and 0.034 mg/kg （k = 2）, respectively.