ABSTRACT
Nitrite is the intermediate oxidation state of nitrogen, both in the oxidation of ammonia to nitrate and in the reduction of nitrate. Such oxidation and reduction occur in wastewater treatment plants, water distribution systems, and natural waters. Total Kjeldahl Nitrogen (TKN) is the sum of free ammonia and organic nitrogen compounds. Organic nitrogen is the difference obtained by subtracting NH3-N from TKN. The sample is heated in the presence of concentrated H2SO4, K2SO4, and HgSO4, and evaporated until SO3 fumes are obtained, and the solution becomes colorless or pale yellow. The residue is cooled, diluted, and made alkaline. The ammonia is distilled and determined by nesslerization, titration, potentiometric, or automated rapid flow analyzer (RFA) method.
