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R9 Laboratory SOP 590
AMMONIA ANALYSIS
Summary
This method is for the determination of ammonia in drinking, surface, and saline waters, domestic and industrial waste.
The colorimetric method is based on reactions which are the same as those in SOP #592, "Analysis of Total Kjeldahl Nitrogen in Water," EPA Method 351.2. The applicable range is 0.3 to 10 mg/L. The range can be extended for high level samples through dilution. The quantitation limit for ammonia is 0.3 mg/L
During the analytical procedure, the sample is neutralized in-line with concentrated buffer on the chemistry manifold of the Lachat QuikChem AE and the ammonium cation is converted to ammonia. The ammonia that is produced is heated at 60°C with salicylate and hypochlorite to produce dark blue-green color, which is proportional to the ammonia concentration. The absorbance is read at 660nm.