新型自动比色法测定饮用水中铝含量的不确定度评定

Evaluation of measurement uncertainty of aluminum in drinking water using a new automatic colorimetric method

目的对饮用水中铝的新型自动比色法进行不确定度评定。方法依据JJF1059.1-2012《测量不确定度评定与表示》,建立数学模型,分析和识别不确定度来源,运用不确定度传播律对新型自动比色法测定饮用水中铝含量的不确定度进行评定。结果用新型自动比色法测定饮用水中铝含量,测量结果为0.111mg/L,合成标准不确定度为0.003mg/L。取包含因子k=2,置信水平约为95%,扩展不确定度为0.006mg/L。结论配制标准系列溶液产生的不确定度分量最大,其次是线性回归,取样体积带来的不确定度分量最小。提示实际工作中,避免使用较小容量器皿配制标准系列溶液可大幅减小测量结果的不确定度。

Objective To evaluate measurement uncertainty of aluminum in drinking water determined by a new automatic colorimetric method. Methods According to Evaluation and Expression of Uncertainty in Measurement （JJF1059.1-2012）, the mathematical model is established, and uncertainty sources are analyzed and identified. The measurement uncertainty of aluminum in drinking water determined by the new automatic colorimetric method is evaluated using law of propagation of uncertainty. Results The concentration of aluminum in drinking water sample determined by the new automatic colorimetric method was 0.11 lmg/L.The combined standard uncertainty was 0.003 mg/L. The expanded uncertainty is 0.006mg/L, using a coverage factor k=2 which gives a level of confidence of approximately 95%. Conclusion The biggest contribution to uncertainty components is preparation of standard solution series, followed by linear regression, and the contribution of sample volume is smallest. In practical work, the t uncertainty of resuhs can be significantly decreased by avoiding the use of small capacity vessels for preparation of standard solution series