对硫酸钡比浊法作为饮用水中硫酸盐测定仲裁法的评价

Discussion on barium sulfate turbidity as arbitration inspection method for sulfate in drinking water

目的通过对GB／T5750．5—2006《生活饮用水标准检验方法无机非金属指标》中硫酸盐的仲裁法——硫酸钡比浊法测定结果的不确定度评定，对该法作为仲裁法的适宜性进行评价。方法根据硫酸钡比浊法的测定方法，对测定过程中的所有不确定度分量进行评定，给出一水样测定结果的扩展不确定度。结果对一水样给出测量结果为250mg／L，扩展不确定度为42mg／L（k=2）。结论硫酸钡比浊法的测量结果不确定度过大，硫酸盐含量的可能分布区间为208—292mg／L，对于卫生标准限值附近的硫酸盐含量不能准确测定，不适于作为生活饮用水中硫酸盐含量测定结果的仲裁法。对测定结果进行不确定度评定有助于选择适宜的仲裁检验方法。

Objective To evaluate the suitability of barium sulfate turbidity in Standard examination methods for drinking water （ GB/T 5750.5--2006） as arbitration inspection method of sulfate in drinking water by evaluation of uncertainty. Methods The expanded uncertainty of determination result for the unknown water sample was given by evaluating all uncertainty components in process of determination of barium sulfate turbidity. Results The determination result of the unknown water sample is 250 mg/L , with the expanded uncertainty of 42 mg/L （k = 2）. Conclusion This method could not accurately determine the amount of sulfate which is close to health standard limited in drinking water, at the same time, it＇ s unsuitable as arbitration inspection method of sulfate in drinking water. Because the expanded uncertainty of determination results of the unknown water sample by barium sulfate turbidity is so big, with the confidence regions of sulfate of 208 - 292 mg/L. So, evaluating uncertainty of the determination results is helpful to choose the suitable arbitration inspection method.