DETERMINATION OF AMMONIA NITROGEN BY SEMI-AUTOMATED

1.1 This method covers the determination of ammonia in drinking, ground, surface, and saline waters, domestic and industrial wastes. 1.2 The applicable range is 0.01-2.0 mg/L NH as N. Higher concentrations can be3 determined by sample dilution. Approximately 60 samples per hour can be analyzed. 1.3 This method is described for macro glassware; however, micro distillation equipment may also be used. 2.0 SUMMARY OF METHOD 2.1 The sample is buffered at a pH of 9.5 with a borate buffer in order to decrease hydrolysis of cyanates and organic nitrogen compounds, and is distilled into a solution of boric acid. Alkaline phenol and hypochlorite react with ammonia to form indophenol blue that is proportional to the ammonia concentration. The blue color formed is intensified with sodium nitroprusside and measured colorimetrically. 2.3 Reduced volume versions of this method that use the same reagents and mola