沸水萃取-紫外可见分光光度法测定金属镀层中六价铬含量的不确定度评定

Evaluation of Uncertainty in Measurement of Hexavalent Chromium(Cr(Ⅵ)) in Coatings on Metals by Boiling Water Extraction-Uv-Vis Spectrophotometry

建立沸水萃取-紫外可见分光光度法测定金属镀层中六价铬含量的不确定度评定方法。建立有效的数学模型,对影响测量过程的不确定度来源进行分析和评定。结果表明:当取置信概率为95%,包含因子K=2,该方法测定金属镀层中六价铬含量的扩展不确定度为U=0.0018μg/cm2,测量结果表示为0.0365±0.0018μg/cm2。样品表面积计算和测量重复性是影响该方法不确定度的主要因素。

The method of evaluation the uncertainty in measurement of hexavalent chromium（Cr（Ⅵ）） in coatings on metals by boiling water extraction-Uv-vis spectrophotometry was established. The sources of uncertainty affecting the measurement process were analyzed and evaluated based on an effective mathematical model. Results showed that the uncertainty of expanded uncertainty of hexavalent chromium in coatings on metals was U=0.0018 μg/cm2 and the results were 0.0365±0.0018 μg/cm2, when the confidence probability was 95 %, comprising a factor K=2. The main factors of the uncertainty were surface area calculation and the measurement repeatability.