Nitrite is an intermediate oxidation state of nitrogen, both in the oxidation of ammonia to nitrate and in the reduction of nitrate. Such oxidation and reduction may occur in wastewater treatment plants, water distribution systems and natural waters. Nitrite can enter a water supply system through its use as a corrosion inhibitor in industrial process water. Nitrite changes the normal form of hemoglobin, which carries oxygen through blood to the rest of the body, into a form called methemoglobin that cannot carry oxygen.

The HI96783-25 are high quality reagents that are pre-measured, allowing for users to achieve fast and accurate colorimetric measurements. These reagents use an adaptation of Standard Methods for the Examination of Water and Wastewater, 23rd Edition, 4500B Diazotization Method, Nitrogen Nitrite. Nitrite is determined through formation of a reddish-purple azo dye produced in acidic solution by coupling diazotized sulfanilamide with aromatic amines.