ICP测试钛酸锂中锂元素含量不确定度评定的讨论

分析了影响等离子发射光谱仪(ICP-OES)测定钛酸锂中锂含量的主要因素,建立数学模型并根据测试过程中的风险因素建立了因果图,给出了各分量不确定度的计算过程。钛酸锂样品中的锂含量检测结果为5.65%,计算出各分量的相对标准不确定度,其中urel(CLi)=0.013,urel(R)=0.012。合成标准不确定度uc=0.11%,置信度区间为95%时,计算得到测试结果的扩展不确定度U=0.22%。同时也可以看出,标准曲线的准确性对合成标准不确定度的贡献很大,对锂元素含量的测试准确性有很大帮助;不确定度的合理利用,可以深入了解测试不确定度各分量的相对标准差。

Discussion on the Uncertainty of Measurement in the ICP-OES Determination of Lithium in Lithium Titanate

The main factors affecting the accuracy of the ICO-OES determination of lithium in lithium titanate were discussed,and the uncertainties of measurements caused by these factors in the determination were evaluated. Mathematical model and causality chart of variables of uncertainty produced in the process of analysis were established. Relative combined standard uncertainty of these factors were calculated,and the process is given. Among them,urel(CLi)is 0.013,urel(R)is 0.012. These two items account for the main part. An combined standard uncertainty of 0.11% was obtained in the determination of 5.65% of lithium titanate,and expanded uncertainty of 0.22% was obtained at 95% confidence level also. At the same time,it can be seen that the accuracy of the standard curve contributes to the combined standard uncertainty,which is also helpful to the accuracy of the lithium element content test. The reasonable use of uncertainty can help us to understand the RSD of each component of the uncertainty.