This is a rapid method, applicable to relatively pure waters. For colored or impure waters, particularly those with an iron concentration greater than 1 mg/1, prior dis illation (see NBN T 91-2 52) is necessary. The method is applicable to water containing between 0.02 and 2 mg of ammoniacal nitrogen per liter without dilution.
NBN T 91-254-1976 history
1975NBN T 91-254-1976 Water analysis methods - Determination of the ammoniacal nitrogen -Direct photometric methodwith sodium phenate