食品添加剂碳酸钙产品中钙含量测定的不确定度评定

摘要

This study evaluated the uncertainty in determination of calcium in food additive calcium carbonate refering to JJF 1059.1-2012 《Evaluation and Expression of Uncertainty in Measurement》.11 parallel determinations were designed,and the average calcium content was 39.54％.According to the measurement function,determine the measurement uncertainty components are measurement repeatability uncertainty,titration volume uncertainty,sample quality uncertainty and other five uncertainty components.The combined standard uncertainty is calculated based on the relative standard uncertainty of each component,then the expanded uncertainty is calculated as U =0.22％,the measurement uncertainty report is obtained as:w =(39.54 + 0.22) ％,k =2.The relative standard uncertainty of each component shows that the largest contribution to the uncertainty component is the standard solution consumed volume uncertainty component,followed by standard solution uncertainty component.%参照JJF 1059.1-2012《测量不确定度评定与表示》,对食品添加剂碳酸钙中钙含量的测定进行不确定度评定.本文设计了11次平行测定,测定结果钙含量平均值为39.54％.根据测量函数关系,确定测量不确定度分量分别是测量重复性的不确定度分量、滴定体积的不确定度分量和试样的质量测量的不确定度分量等八个不确定度分量.根据各分量的相对标准不确定度计算合成标准不确定度,再计算出扩展不确定度U=0.22％,得出测量不确定度报告:w=(39.54±0.22)％,k=2.由各分量的相对标准不确定可知,对不确定贡献最大分量是标准溶液消耗体积的不确定度分量,其次是标准溶液的不确定度分量.