From the point of view of hygiene, the presence of ammonia is almost always a cause for concern since its occurrence is primarily due to the decomposition of nitrogenous organic substances. In some cases, e.g., in waters particularly rich in iron, ammonia is formed through the reduction of nitrate.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
Ammonium ions react at a pH of approx. 12.6 with hypochlorite ions and salicylate ions in the presence of sodium nitroprusside, which serves to catalyze the reaction, to form a green color (indophenol blue).