Interlaboratory Proficiency Test 08/2017 - Domestic water measurements

Abstract

Proftest SYKE carried out the proficiency test for analyses of raw and domestic drinking waters to which 45 participants took part. The performance of the participants was evaluated by using z scores. In this proficiency test 89 % of the results were satisfactory when the standard deviation for performance assessment varied between 5 and 25 %, and 0.2 units for pH, of the assigned value at the 95 % confidence interval. The amount of accepted results was similar to the previous round. The homogeneity and the stability of the samples (pH, NH4 and alkalinity) were tested and the samples were regarded to be sufficient homogenous and stable. Significant different results were observed for alkalinity results using two-point potentiometric titration with HCl (EN ISO 9963-1, national supplement) compared to results from one point titration with HCl according to SFS3005. Warm thanks to all the participants of this proficiency test!