X射线荧光光谱法测定稻谷样品中的Cd不确定度评定

Evaluation of uncertainty in Cd measurement of paddy samples by x-ray fluorescence spectrometry

对用X射线荧光光谱法测定稻谷样品中Cd的不确定度进行了评定,其不确定度的来源主要是校准曲线的建立及未知样品浓度的回归计算引入的不确定度,其次是标准物质的标准不确定度,重复测量和仪器综合稳定性引入的标准不确定度影响较小。在对各个不确定度分量进行量化的基础上,通过合成得到的检测结果的标准不确定度,乘以95%置信概率下的扩展因子2,得到测量结果的扩展不确定度。

The uncertainty of cadmium in paddy samples determined by X-ray fluorescence spectrometry was evaluated. The uncertainty was mainly caused by the establishment of calibration curve and the regression calculation of unknown sample concentration. The secondary source of uncertainty was the uncertainty of standard materials, followed by the repeated measurement and instrument stability. Based on the quantitative analysis of each source, the standard uncertainty of the synthesized detection result was multiplied by the extented factor 2 under the 95% confidence probability to obtain the extented uncertainty of the measurement result.