酸度计法测定酱油中氨基酸态氮的不确定度评价

该文分析了滴定法测定酱油氨基酸态氮不确定度来源，对不确定度各分量进行评估与合成。结果表明，样品移取、定容和滴定引入的体积不确定度以及pH计示值误差和分辨率引入的不确定度分量是影响酱油氨基酸态氮测定的主要来源。试验对酱油样品进行10次重复测定，测得氨基酸态氮为0.813 g/100 mL，扩展不确定度为0.046 g/100 mL（P=95%，k=2）。该不确定度评定适用于滴定法测定酱油中氨基酸态氮的过程分析，对检测结果准确度的控制具有指导意义。

Uncertainty evaluation of determination of amino acid nitrogen in soy sauce by acidity meter method

In this paper, the sources of uncertainty in the determination of amino acid nitrogen in soy sauce by titration were analyzed, and each component of uncertainty was evaluated and synthesized. The results showed that the volume uncertainty introduced by sample removal, constant volume and titration, as well as the uncertainty components introduced by pH meter indicating error and resolution were the main sources of influencing the determination of amino acid nitrogen in soy sauce. The amino acid nitrogen content was 0.813 g/100 ml with the expanded uncertainty value 0.046 g/100 ml (P=95%, k=2) by parallel determination of soy sauce 10 times. The evaluation of uncertainty was suitable for the process analysis of amino acid nitrogen in soy sauce by titration, and had guiding significance for the control of the accuracy of detection results.