Determination of trace amounts of nitrite by derivatisation and gas chromatography

Abstract

A gas-chromatographic method for the determination of nitrite is described. Nitrite is converted into substituted benzene derivatives by reaction with substituted anilines and hypophosphorous acid, and the resulting benzene derivatives are determined by gas chromatography. The derivatisation yields of nitrite were studied by using anilines with various substituents that have a high response to an electron-capture detector. Nitroanilines give high yields and m-nitroaniline is the most suitable derivatisation reagent for determining trace amounts of nitrite. By using m-nitroaniline and an electron-capture detector, the detection limit and determination range of nitrite are 0.5 ng ml^–1 and up to 1.00 µg ml^–1, respectively, which are much lower than those of the widely used colorimetric method for the determination of nitrite (detection limit 16 ng ml^–1). River water samples containing nitrite were analysed by both this gas-chromatographic method and the colorimetric method.