离子色谱法同时测定饮用水中5种消毒副产物的不确定度评定

目的 评定离子色谱法同时测定饮用水中5种消毒副产物含量的不确定度。方法 按照GB/T 5750.10-2006《生活饮用水标准检验方法消毒副产物指标》进行饮用水中溴酸盐、二氯乙酸、三氯乙酸、亚氯酸盐、氯酸盐含量的测定。应用测量不确定度评定理论, 分析测量不确定度的来源并对各分量进行不确定度评定, 计算合成标准不确定度和绝对扩展不确定度, 明确对测试结果有重要影响的分量。结果 在95%的置信区间内, 样品中5种消毒副产物溴酸盐、二氯乙酸、三氯乙酸、亚氯酸盐和氯酸盐的含量依次为(2.00±0.075)、(2.04±0.062)、(0.99±0.054)、(12.6±0.35)、(9.41±0.24) mg/L (k = 2)。结论 影响测量不确定度的主要因素是曲线拟合产生的不确定度和由标准溶液引入的不确定度。实验中应该提高标准溶液配制的准确性和标准曲线测定的精密度。

Uncertainty evaluation for the simultaneous determination of 5 kinds of disinfection by-products in drinking water by ion chromatography

Objective To evaluate the uncertainty for the simultaneous determination of 5 disinfection by-products content in drinking water by ion chromatography. Methods According to GB/T 5750. 10-2006 Standard test methods for drinking water disinfection by-products indicators, the content of bromate, dichloroacetic acid, trichloroacetic acid, chlorite, chlorate in drinking water was measured. Applying the evaluation theory of measurement uncertainty, the source of measurement uncertainty was analyzed, the uncertainty of each component was evaluated, the composite standard uncertainty and the absolute extended uncertainty was calculated, and the components those had important influence on the test results were defined. Results Within the 95% confidence interval, the content of the 5 disinfection byproducts bromate, dichloroacetic acid, trichloroacetic acid, chlorite, and chlorate in the sample was (2.00±0.075), (2.04±0.062), (0.99±0.054), (12.6±0.35), (9.41±0.24) mg/L (k = 2). Conclusion The main factors affecting the uncertainty of measurement are the uncertainty generated by curve fitting and the uncertainty introduced by standard solution. The accuracy of standard solution preparation and the precision of standard curve determination should be improved in the experiment.