水中总硬度测定的不确定度评定

Uncertainty in the Determination of Hardness in Water

目的探讨水中总硬度测定的不确定度评价方法。方法按《生活饮用水卫生规范》(2001)的乙二胺四乙酸二钠容量分析法测定了某水样的总硬度,参考JJF1059-1999建立了水中总硬度测定的数学模型并进行了计算。分析了相对不确定度的方差合成并给出了各不确定度分量的详细评定过程。结果按数学模型计算该水样的总硬度为137mg/L。水中总硬度测定的相对不确定度为0.008,扩展不确定度为3mg/L,不确定度的表达为(137±3)mg/L。结论该方法对评价水中总硬度测定的容量分析法的不确定度有一定的参考价值。

Objective To explore the methods for the evaluation of the uncertainty of the determination of hardness in water. Methods A certain water sample was analyzed for the hardness according to EDTA-Na2 volumetry ruled by the Sanitory Standard for Drinking Water(2001).The mathematical model of the determination of hardness in water was established based on JJF1059-1999. The variance composition of the relative uncertainty was analyzed. The procedure of the evaluation of every uncertainty component was described in detail. Results The hardness in the water sample was 137 mg/L calculated according to mathematical model established in this study. The relative uncertainty and the expand uncertainty of the detection of hardness in the water sample were 0.008, 3 mg/L respectively. The expression of the uncertainty in the determination of hardness was (137±3)mg/L. Conclusion This method presented referable value for the evaluation of the uncertainty of volumetry determination method of hardness in water.