气相色谱法测定乳粉中1,2-丙二醇含量的不确定度评定

Evaluation of Uncertainty in the Determination of 1,2-Propanediol in Milk Powder by Gas Chromatography

采用气相色谱-氢火焰离子化检测器(gas chromatography-flame ionization detector, GC-FID)对乳粉中1,2-丙二醇的含量进行测定,以此为基础进行测量不确定度的评定。通过创建测量1,2-丙二醇含量的数学模型,评估影响其测量结果的不确定度来源,最终形成该方法检测乳粉中1,2-丙二醇含量的不确定度评价方法。结果表明,样液浓度、体积、样品质量和结果重复性是影响结果不确定度的主要分量,其相对标准不确定度分别为:2.60%、0.259%、0.0203%和0.698%。分析整体的检测过程发现,标准溶液配制过程中所用的量器以及标准曲线拟合过程引入的不确定度贡献相对较大,最终得到乳粉中1,2-丙二醇的含量范围为0.123±0.00664g/kg(k=2,置信概率P=95%)。该研究数据可作为GC-FID法测量乳粉中1,2-丙二醇含量的不确定度评价依据,能满足乳粉中1,2-丙二醇检测结果的规范性表达,同时为该方法检测过程的质量保证提供指导。

The content of 1,2-propanediol in milk powder was determined by gas chromatography-flame ionization detector(GC-FID),and the measurement uncertainty was evaluated on this basis.By establishing a mathematical model for measuring the content of 1,2-propanediol,the sources of uncertainty affecting the measurement results were evaluated.Finally,the uncertainty evaluation method for the determination of 1,2-propanediol in milk powder was obtained.The results shown that the concentration and the volume of the sample solutions,the weight of the samples and the repeatability of the determination results were the main components affecting the uncertainty,and their relative standard uncertainties were 2.60%,0.259%,0.0203%and 0.698%,respectively.Through the analysis of the whole detection process,it was found that the measuring instrument used in the standard solution preparation process and the fitting of standard curve contributed a lot to the uncertainty introduced.The content range of 1,2-propanediol in milk powder was(0.123±0.00664)g/kg(k=2,p=95%).The data in this study can be used as the basis for evaluating the uncertainty of the determination of 1,2-propanediol in milk powder by GC-FID,and can meet the standard expression of the determination results.At the same time,it provided guidance for the quality assurance of the detection process of this method.