分光光度法测定地面水中六价铬不确定度评定

Evaluation of Uncertainty in Determination of Hexavalent Chromium in Surface Water by Spectrophotometry

依据《化学分析中不确定度的评估指南》和国标为GB/T 7467-1987的二苯碳酰二肼(英文简称DPCI)分光光度法对水中六价铬的不确定度进行测定,该法测定样品中六价铬的含量在计算与评定后所得结果为0.036 mg/L时,取k=2(包含因子,置信概率在95%左右),U=0.001mg/L(即拓展不确定度)。在实际的工作中,此不确定度评价方法所能够发挥出的实际作用很大。

The uncertainty of hexavalent chromium in water was determined according to "Guide to the Evaluation of Uncertainty in Chemical Analysis" and DPCI spectrophotometry with GB/T 7467-1987,through calculation and evaluation,it is concluded that the content of Cr(Ⅵ) in samples determined by this method is 0.036 mg/L, the inclusion factor K=2(about 95 % confidence probability), and the expanded uncertainty U=0.001 mg/L. The uncertainty evaluation method has strong practical value in practical work.