scope:

This pre-standard describes a method for the sample preparation of water containing sulphuric acid and potassium sulphate, where nitrogen and phosphorus compounds are converted in such a way as to allow the same sample to be used for a photometric determination of the sum of the contents of ammoniacal nitrogen and organically bound nitrogen according to NEN 6646, and of the total content of phosphorus compounds according to NEN 6663, by continuous flow analysis. The pre-standard applies to water with of content of ammoniacal nitrogen and organically bound nitrogen of at least 0.05 mg/l of N and with a total content of phosphorus compounds of at least 0.01 mg/l of P.