Spectrophotometric determination of nitrite based on its catalytic effect on the reaction of nuclear fast red and potassium bromate

A highly selective and sensitive catalytic spectrophotometric method was developed for the determination of nitrite in water samples. The method is based on its catalytic effect on the nuclear fast red-potassium bromate redox reaction in acidic medium. The reaction was followed spectrophotometrically by measuring the change in the absorbance at 518 nm of nuclear fast red 5 min after initiation of the reaction. In this study, the experimental parameters were optimized and the effects of other cations and anions on the determination of nitrite were examined. The calibration graph was linear in the range 2.0-45 mu g mL(-1) of nitrite. The relative standard deviations for the determination of 15 and 30 mu g mL(-1) of nitrite were 3.1 and 1.75 %, respectively (n = 8). The detection limit calculated from three times the standard deviation of the blank 3Sb was 0.7 mu g mL(-1). The method was successfully applied to the determination of nitrite in spiked tap, natural and wastewater samples.