分光光度法测定水中六价铬测量不确定度评定

Uncertainty Evaluation of Analyzing Cr(Ⅵ) in Water by Diphenylcarbazide Spectrophotometry

根据国标生活饮用水标准检验方法中检测饮用水中六价铬的原理、方法并结合分析整个实验流程中各不确定度分量来源的数学模型,得出该实验方法的不确定度。通过计算和评定,得出该法测定水中六价铬的测量结果为0.040 mg/L时,取包含因子k=2(约95%置信概率),扩展不确定度U=0.001 mg/L。该法对水中六价铬的测量不确定度评定很有必要、该不确定度评定方法对提高实际工作的准确度具有一定的指导意义。

According to the principle and method of testing Cr( Ⅵ) in drinking water in the national standard for drinking water,and combining with the mathematical model for analyzing the sources of uncertainty components in the whole experimental process,the uncertainty of the experimental method was obtained. The result showed that the extended uncertainty U = 0. 001 mg/L,when the concentration of Cr( Ⅵ) was 0. 040 mg/L,and the coverage factor k = 2( confidence probability was 95%). It was necessary to evaluate the measurement uncertainty of Cr( Ⅵ) in water,and the uncertainty evaluation method had certain guiding significance for improving the accuracy of practical work.