Photochemical reduction of nitrate to nitrite in aqueous solution and its application to the determination of total nitrogen in water

Abstract

An equilibrium between nitrate and nitrite exists under UV irradiation, and in alkaline solution nitrate can be 93% reduced to nitrite within 8 min. This property has been applied to the determination of total nitrogen in environmental water samples. The coefficient of variation is 1.94% for river waters with a total nitrogen concentration of 1.80 mg l^–1. A total nitrogen determination can be completed within 1 h by this manual procedure. A modification to the colour development for nitrite determination was made, which was used when the nitrite concentration was higher than 0.3 mg l^–1.