Determination of nitrite and nitrate in Venice lagoon water by ion interaction reversed-phase liquid chromatography

Ion interaction reversed-phase liquid chromatography with octylammonium orthophosphate as the interacting reagent and a reversed-phase C₁₈ column was applied to the identification and determination of nitrite and nitrate in Venice lagoon water. Interference by the high chloride concentration was systematically studied and the results obtained with different column packings were compared. With spectrophotometric detection at 230 nm, nitrite at 0.005 mg 1^?1 can be detected and determined even in the presence of 0.70 M chloride. The dependence of the retention time of nitrite on the chloride concentration was studied for two reversed-phase columns with different packings. Concentrations of 0.30 ± 0.05 mg 1^?1 of nitrite and 0.20 ± 0.05 mg 1^?1 of nitrate were found in Venice lagoon water.