地质样品铷锶钇锆元素偏振能量色散X射线荧光光谱分析结果不确定度的评估

The Evaluation of Uncertainty in the Results for Elements Rubidium,Strontium,Yttrium and Zirconium in Silicate Geological Samples by Polarized Energy Dispersive X-Ray Fluorescence Spectrometry

建立了一种以相对误差的标准偏差统计不确定度的评估方法。运用镶边压片技术制备样片,用Spectro X-Lab 2000型偏振能量色散X射线荧光光谱(P-EDXRF)仪器分析硅酸盐基体的76个国家一级标准物质和89个地质行业多目标考核样品,研究表明165个样品Rb,Sr,Y和Zr元素测量结果的相对误差符合正态分布(置信度为95%)。以此为依据,分段统计相对误差的标准偏差作为对应浓度段被测量结果的总相对不确定度,扩展因子为2。分段统计精密度引起的相对不确定度,剥离出准确度引起的相对不确定度。不同元素准确度引起的相对不确定度在总不确定度中所占比例不同。通过"实验室测量审核结果公式"和"标准值及其扩展不确定度与测试修正值及其扩展不确定度的比较"两种方式,验证了总相对不确定度统计方式具有合理性。

A method for evaluation of uncertainty was established with standard deviation of relative error.Utilizing a polarized energy dispersive X ray fluorescence spectrometer（P-EDXRF）X-lab 2000 with pressed polyethylene-backed pellets,76 national reference materials and 89 geological examination samples were analyzed,the results indicated that the relative errors consist with the normal distribution with confidence level 95%.The section standard deviations of relative errors acted as method global relative uncertainty and expanded factor was 2.The section relative uncertainty caused by precision was analyzed and relative uncertainty caused by accuracy based on the error transfer formula was isolated.The ratio of relative uncertainty caused by accuracy to the global relative uncertainty was different with different levels and elements.Two methods validated that the evaluation of global uncertainty is reasonable,with the first method being the formula of audited results in laboratory,and the second being the comparison of standard value with expanded uncertainty and a revised value with expanded uncertainty.