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

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.

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.

The determination result of the unknown water sample is 250 mg/L , with the expanded uncertainty of 42 mg/L (kappa = 2).

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.