Kinetic spectrophotometric determination of nitrite by the catalytic oxidation of bromocresol purple with potassium bromate

A kinetic spectrophotometric method for the determination of nitrite was developed, based on the catalytic oxidation of bromocresol purple with KBrO3 at 22 similar to 28 degrees in 0.45 mol/mL H3PO4 medium. The temperature had great effect only on the initial reaction rate. The DeltaA kept constant during 10 similar to 22 min. Fixed at 12 min, the linear range and detection limit for nitrite at 434 rim were 0.01 similar to0.4 mg/L and 9 mug/L, respectively. Most of the common ions did not interfere. Fe(III) could be masked with NaF. The effect of V(V) was eliminated by preparing blank sample solution with urea. The method is sensitive and selective. It was applied to the determination of trace nitrite in water with satisfactory results.