ABSTRACT
Nitrogen compounds are members of the inorganic nutrient group, and the wide variety of forms of nitrogen in environmental samples have great interest. Ammonia is mostly produced by decomposition of organic nitrogen-containing compounds and by the hydrolysis of urea. The yellow color characteristic to low ammonia nitrogen concentration can be measured with acceptable sensitivity within the wavelength region of 400 to 425 nm when a 1 cm light path is available. For high ammonia concentrations, a distillation and titration technique is preferred. The titrimetric method is used only on samples that have been carried through preliminary distillation. Automated phenate method is used to determine ammonia nitrogen in potable, surface, and saline waters. This method is also applicable to domestic and industrial wastewaters over a range of 0.02 to 2.0 mg/L when photometric measurement is made at 630 to 660 nm in a 15 mm or 50 mm tubular flow cell.
