The method describes how to determine the nitrite content of water photometrically with a cuvette test.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
Nitrite ions are undesirable in drinking water generally and therefore in the water for use in the food industry as well; their presence serves as an indicator for bacterial activity and fecal contamination. Generally, small quantities are found in surface waters, and in groundwater only rarely (e.g., in groundwater containing iron, nitrites can form from nitrates through inorganic reduction); at higher concentrations (> 1 mg/l), nitrites can be found in wastewater.
In an acidic solution, nitrite reacts with primary aromatic amines, producing diazonium salts. Together with aromatic compounds, they form azo compounds, which contain an amino or hydroxyl group and exhibit an intense color.