分光光度法测定蛋白饮料中蛋白质含量的不确定度评定

目的对分光光度法测定蛋白饮料中蛋白质含量的不确定度进行评定。方法根据JJF1059.1-2012标准要求,以测定蛋白饮料中蛋白质含量为例,分析不确定度的主要来源并定量,计算相对合成标准不确定度,从而评定扩展不确定度。结果蛋白饮料中蛋白质含量为5.66 g/100 g,扩展不确定度为0.20 g/100 g (95%,k=2)。测量结果的不确定度主要来源于分光光度法标准曲线的拟合,测量重复性与氨氮标准溶液的影响次之,而样品的称量和样品的定容带来的影响可忽略不计。结论该评价方法及结果能提高实际工作中蛋白质检测的准确性。

Evaluation of uncertainty in determination of protein content by spectrophotometry determination in protein beverage

Objective To evaluate the uncertainty of the determination of protein content in protein drinks. Methods According to the JJF 1059.1-2012 standard requirement, the main source of uncertainty was analyzed by quantitative determination of protein content in protein beverages, and the relative synthetic standard uncertainty was calculated to evaluate the extended uncertainty. Results The concentration of protein was 5.66 g/100 g and the expanded uncertainty was 0.20 g/100 g (95%, k=2). The uncertainty of the measurement results mostly came from the standard curve fitting, the influence of measurement repeatability and ammonia nitrogen standard solution was the second, while the influence of constant volume and sample weighing could be ignored. Conclusion The evaluation method and results can improve the accuracy of protein detection in practical work.