Spectrophotometric determination of nitrite in polluted waters using 3-nitroaniline

Abstract

Nitrite reacts with 3-nitroaniline in the presence of hydrochloric acid to form a diazonium cation, which is subsequently coupled with N-(1-naphtyl)ethylenediammonium chloride to form a stable purple azo dye. The method is suitable for the determination of 0.01–0.80 μg ml −1 nitrite. The reactions are very fast and require no control of temperature. The observed molar absorptivity and Sandell's sensitivity of the azo dye are 4.9 × 10 4 l mol −1 cm −1 and 9.4 × 10 −4 μg cm −2, respectively. The method is free from most interferences. The method has been applied successfully to polluted river water.