New Test Method for Determination of Total Nitrogen by Alkaline Persulfate Digestion and Colorimetry
1. Scope
This method determines total nitrogen, and TKN by calculation, after a heated alkaline persulfate digestion. Nitrogen compounds are converted to nitrate ions. The nitrate ions react in acidic solution with 2,6-dimethylphenol to form a nitrophenol compound which is read at maximum absorption by a photometer or spectrophotometer.
Keywords
environmental nutrients, test kit, sTKN,
Rationale
THis method is based on the HACH sTKN method that is approved at 40 CFR Part 136, however, the HACH method is approved only for TKN. The method anticipates future EPA approval of TN and this provides users with a VCSB alternative that can use any test kits.