EDTA络合滴定法测定地下水中硬度的不确定度评定

Evaluation on uncertainty of hardness measurement of groundwater using EDTA complexometric titration

依据JJF 1059—1999《测量不确定度评定与表示》的要求,结合测量重复性、标定钙标准溶液和滴定等影响因素对测量不确定度的影响分析,对采用EDTA络合滴定法测定某地下水中硬度的测量不确定度进行了评定。建立了地下水中硬度测定的数学模型,并按数学模型计算地下水中的硬度。标定钙标准溶液为影响地下水中硬度测量不确定度的主要因素,当置信水平95%时,可得出某地下水中硬度的测量不确定度为(137±0.4)mg/L。

The uncertainty of hardness measurement of groundwater,using EDTA complexometric titration is evaluated in this paper.Based on JJF 1059—1999 ＂Evaluation and Expression of Uncertainty in Measurement＂,the mathematical model of groundwater hardness measuring is established,and the groundwater hardness is calculated according to the mathematical model.The unfluencing of measuring repeatability,calibrating standard solution of calcium and titration are fully considered,and the main factor is calibrating standard solution of calcium.According to these factors,the uncertainty of measurement of groundwater hardness is（137±0.4） mg/L in the level of 95% confidence level.