微生物法测定婴幼儿配方乳粉中叶酸含量的不确定度评定

Uncertainty Evaluation for the Determination of Folic Acid in Infant Formula Milk Powder by Microbiological Method

目的:评估微生物法测定婴幼儿配方乳粉中叶酸含量的测量不确定度。方法:依据《食品微生物定量检测的测量不确定度评估指南》(RB/T 151—2016)及《食品安全国家标准食品中叶酸的测定》(GB 5009.211—2022)评估测试过程中各主要因素引入的相对标准不确定度分量,进而对其进行合成与扩展。结果:当试样叶酸含量为66.1μg/100 g时,其扩展不确定度为5.2μg/100 g,包含因子k=2,置信概率95%。结论:重复性测量、标准物质称量、标准溶液配制及系列管制备、标准曲线拟合等测量不确定度分量对检测结果的影响较大。

Objective:To establish an uncertainty evaluation method for the determination of folic acid in infant formula milk powder by microbiological method.Method:According to RB/T 151—2016 and GB 5009.211—2022,the components of measurement uncertainty generated in the process of determining folic acid content in infant formula milk powder by microbiological method were analyzed,and the combined standard uncertainty and expanded uncertainty of measurement results were calculated.Result:When the folic acid content of the sample was 66.1μg/100 g,with an expanded uncertainty was 5.2μg/100 g,with a coverage factor of k=2 and a confidence probability of 95%.Conclusion:The uncertainty components such as repeatability measurement,standard substance weighing,standard solution preparation and serial tube preparation,and standard curve fitting have a great impact on the test results.