高效液相色谱法检测饮料中阿斯巴甜的含量的不确定度评估

摘要

[目的]评估高效液相色谱法检测饮料中阿斯巴甜含量的不确定度.[方法]用高效液相色谱法测定饮料中阿斯巴甜的含量,对整个测量过程的不确定度来源进行分析,并对不确定度各分量进行了评估和合成.[结果]用GB/T 22254-2008<食品中阿斯巴甜的测定>方法重复6次测定饮料中阿斯巴甜平均含量为(0.806±0.038)g/kg,k=2.影响过程不确定度的主要来源为样品称量过程、样品定容体积所引入标准溶液的配制过程、拟合标准曲线所引入的不确定度.①标准工作液的不确定度.标准工作液的合成不确定度为0.013 9,包括标准样品纯度引入的不确定度0.005 8、标准物质称量引入的标准不确定度1.49×10-4、阿斯巴甜标准储备液配制过程中玻璃器具校准产生的相对不确定度0.007 88、标准工作溶液配制过程中玻璃器具校准产生的不确定度0.009 9.②样品试样制备过程引入的不确定度.包括样品称量过程的相对标准不确定度0.009和样品定容过程引入的不确定度0.000 78.③标准曲线拟合过程不确定度.曲线拟合的相对不确定度为0.002 46.阿斯巴甜测定结果的不确定度为0.017 0,合成总的相对标准不确定度为0.023 9,扩展标准不确定度为0.019.[结论]标准溶液、标准曲线和重复性的不确定度分量是不确定度的主要来源,待测样品的称量和定容的不确定度分量占的比例不大.%[Objective] The aim was to evaluate the uncertainty of determining aspartame in beverage by high performance liquid chromatography (HPLC). [Method] The content of aspartame in beverage was determined by HPLC, then the source of uncertainty in the whole determination process was analyzed, and each component of uncertainty was evaluated and combined. [Result] Through 6 repeated determinations by the method in GB/T 22254-2008 "Determination of Aspartame in Food", the average content of aspartame in beverage was (0.806±0.038) g/kg, and k=2. The main sources of uncertainty to affect the process were the sample weighting process, the preparation process of standard solution introduced by sample constant volume and the uncertainty introduced by fitting standard curve. ①The uncertainty of standard work-solution. The combined uncertainty of standard work-solution was 0.013 9, among them the uncertainty introduced by standard sample purity was 0.005 8, the standard uncertainty introduced by standard material weighting was 1.49×104, the relative uncertainty introduced by glass apparatus calibration in the preparation process of aspartame standard reserving solution was 0.007 88, and the uncertainty introduced by glass apparatus calibration in the preparation process of standard work-solution was 0.009 9. ②The uncertainty introduced by the preparation process of sample specimen. Among them the relative standard uncertainty introduced by sample weighting process was 0.009, and the uncertainty introduced by sample constant volume was 0.000 78. ③The uncertainty introduced by the fitting process of standard curve. Among them the relative uncertainty of curve fitting was 0.002 46, the uncertainty introduced by the determined results of aspartame was 0.017 0, the total combined standard uncertainty was 0.023 9, and the expanded standard uncertainty was 0.019. [Conclusion] The uncertainty components of standard solution, standard curve and repeatability are the main sources of uncertainty, while those of sample weighting and sample constant volume account for little proportion.