摘要目的 建立生活饮用水中碘化物的砷铈催化分光光度法的测量不确定度评估方案,评定测定结果的质量和主要影响因素;建立该方法工作曲线的变动性不确定度评估计算公式;建立移液器带来的不确定度评估方案.方法 按照《适合缺碘及高碘地区水碘检测的方法研究》方法要求,从测量的重复性、工作曲线的变动性、标准溶液的不确定度和样品溶液体积不确定度等方面,分析两个浓度的国家标准样品(GBW09114c、GBW09113c)不确定度分量.结果 国家标准样品GBW09114c和GBW09113c中碘化物浓度经修约后分别为(61.3±1.4)、(8.1±0.3)μg/L;相对扩展不确定度RU和RU2分别为2.25％、3.46％,均在标准物质证书允许的误差范围内(10.0％、14.8％).测量的重复性、标准溶液的不确定度中碘化钾基准试药不确定度、玻璃器材不确定度、样品溶液体积不确定度中移液器不确定度为主要影响因子;提出了更符合检测实际工作曲线的变动性不确定度计算公式;将温度影响因素和操作重复性引入移液器的不确定度讨论中.结论 此方法适用于评估生活饮用水中碘化物的砷铈催化分光光度法的不确定度.

abstractsObjective We set up an uncertainty assessment method for determination of iodides in water by As3+-Ce4+ catalytic spectrophotometry, in order to assess the accuracy of the method and the major influencing factors, and to build up an equation to assess the uncertainty in the mobility of working curve and an uncertainty assessment method for pipettors.Methods According to "Methods for Water Iodine Detection Suitable for Iodine Deficiency and Iodine Excess Areas", the uncertainty items of the two standard materials (GBW09114c and GBW09113c) in different concentrations, such as repeatability of measurement, the mobility of working curve, the uncertainty of standard solution and sample solution, etc, were analyzed.Results The contents of iodide in GBW09114c and GBW09113c were (61.3 ± 1.4) and (8.1 ± 0.3)μg/L;relative expanded uncertainty RU1 and RU2 were 2.25％ and 3.46％, both of them were in the range of acceptable deviation in the standard material certification (10.0％ and 14.8％).Major influencing factors were repeatability of measurement, the uncertainty of standard solution (including the uncertainty of potassium iodide reference reagent and glass equipment), and the uncertainty of sample solution (including the uncertainty of pipettors).A more adaptable equation for the mobility of working curve had been proposed;the factors involved in environment temperature and operation repeatability were used as the items of the pipettors' uncertainty.Conclusion This method can be used to assess the uncertainty in determination of water iodides by As3+-Ce4+ catalytic spectrophotometry.