Rapid determination of nitrate and nitrite in drinking water samples using ioninteraction liquid chromatography

A simple ion-interaction chromatographic method for the fast determination of nitrate and nitrate at trace concentrations in water samples is described. Using a short 3.0 cm×0.46 cm 3 mum ODS analytical column together with a mobile phase containing 20 mM of the ioninteraction reagent tetrabutylammonium chloride (TBA-Cl), nitrite and nitrate could be readily separated from each other and other common UV absorbing anions in under 50 s. With the addition of a peristaltic pump and in-line filter, the developed method was configured for continuous monitoring of nitrate and nitrite concentrations in real tap water samples. Up to 60 analyses/h could be carried out using the on-line system, which matches the analysis rate possible with traditional flow injection analysis (FIA) based methods. Standard analytical performance criteria were evaluated with nitrite being detectable at concentrations as low as 5 mug/l in actual tap water samples containing up to a 1000-fold excess of nitrate. Results obtained using the fast ion-interaction method compared well to those obtained using a conventional ion chromatographic method.