杜马斯定氮法测定车用尿素水溶液中尿素含量的不确定度评定

Uncertainty Evaluation of Rapid Determination of Urea Content in AUS32 by Dumas Method

为了研究杜马斯定氮法测定车用尿素水溶液中尿素含量的准确性,通过试验对检测过程中产生的缩二脲测定、样品称量、标准品纯度、定氮仪误差及重复性误差等不确定因素进行分析,建立数学模型,进行不确定度评定。结果表明,杜马斯定氮法测定车用尿素水溶液中尿素含量合成不确定度为1.43%,准确性良好;定氮仪系统误差、标准品纯度和测量重复性是影响测量准确性的主要因素,在测量过程中应严格把控。

This study aimed to evaluate the uncertainty of measurement in rapid determination of urea content in AUS32 by Dumas method.Through experiments,the uncertain factors such as biuret determination,sample weighing,standard product purity,nitrogen analyzer error and repeatability error generated during the detection process were analyzed,and a mathematical model was established to evaluate the uncertainty.The results show that the combined uncertainty of the urea content in the vehicle urea aqueous solution determined by the Dumas method is 1.43%,and the accuracy is good;The system error of the nitrogen analyzer,the purity of the standard product and the measurement repeatability are the main factors affecting the measurement accuracy,in the measurement process should be strictly controlled.