A novel kinetic determination of nitrite based on the perphenazine-bromate redox reaction

An extremely sensitive and selective kinetic method was developed for the determination of trace levels of nitrite based on its catalytic effect on the oxidation of perphenazine (PPZ) with bromate in a phosphoric acid medium. The reaction rate was monitored spectrophotometrically by tracing the formation of the red-colored oxidized product of PPZ at 525 nm within 30 sec of mixing. The optimum reaction conditions were 4.0 mu mol L-1 PPZ, 0.4mol L-1 H3PO4 and 30 mmol L-1 bromate at 25 degrees C. Using the recommended procedure, nitrite could be determined with a linear calibration graph up to 4.50 ng mL(-1) and a detection limit of 0.07 ng mL(-1). The method was conveniently applied to the determination of nitrite in samples of rain, polluted well and formulated waste waters. Moreover, the published kinetic spectrophotometric methods for nitrite determination are reviewed.