分光光度法测定空气中甲醛不确定度评定

采用分光光度法测定空气中甲醛,对测定结果的不确定度进行评定。采用酚试剂分光光度法测定空气中甲醛,分析测定过程中的各项不确定度来源,包括样品采集、标准工作溶液配制、标准工作曲线拟合、测定仪器以及重复测定等引入的不确定度,计算合成不确定度,最后获得相对扩展不确定度。当空气中甲醛质量浓度为0.0244~0.2218 mg/m^3时,测定结果在95%置信区间时的相对扩展不确定度为0.1172(k=2)。不确定度主要来源于A类不确定度和系列标准工作溶液制备、标准工作曲线拟合、水中甲醛溶液标准物质的稀释引入的不确定度。

Uncertainty evaluation of formaldehyde in the air determined by spectrophotometry

The formaldehyde in the air was determined by spectrophotometry,and the uncertainty of measurement results was evaluated.Formaldehyde in the air was determined by phenol reagent spectrophotometry.The sources of uncertainty in the determination process were analyzed,including the uncertainty introduced by sample collection,preparation of standard working solution,fitting of standard working curve,measuring instrument and repeated measurement.The synthetic uncertainty was calculated and the relative expanded uncertainty was obtained.When the formaldehyde mass concentration in the air was in the range of 0.0244-0.2218 mg/m^3,the relative expanded uncertainty of the measurement results was 0.1172(k=2)at 95%confidence interval.The uncertainty are mainly derived from the uncertainty of class A and the uncertainty of series standard working solution preparation,standard working curve fitting and dilution of standard substance of formaldehyde solution in water.