Sensitive determination on nitrite using its catalytic effect on the bromate oxidation of prochlorperazine

A highly sensitive and selective catalytic method is described for the determination of trace amounts of nitrite based on its effect on the oxidation of prochlorperazine (PCP) with bromate. The reaction rate was monitored spectrophotometrically by following the formation of the red oxidation product of PCP at 525 nm, within 1 min of mixing the reagents. The optimum reaction conditions were 40 mu mol l(-1) PCP, 0.20 mol l(-1) H3PO4 and 10 mmol l(-1) bromate at 25 degrees C. A 1 mmol l(-1) EDTA concentration and 2 mu mol l(-1) Hg-II were used as effective masking agents for vanadium and iodide ions, respectively. By using the recommended procedure, the calibration graph was linear up to 70 ng ml(-1) of nitrite; the detection limit was 0.8 ng ml(-1). The method was applied to the determination of nitrite in rain and polluted river waters.