Catalytic Spectrophotometric Determination of Trace Amount of Nitrite in Water Using Reaction System of Aniline Blue and Potassium Bromate

In H2SO4 solution, the oxidative fading reaction of potassium bromate was catalyzed by nitrite. Based on this reaction, a catalytic spectrophotometric method for the determination of trace amount of nitrite was proposed. The optimized conditions were as follows: ① amount of 1.0 mol·L-1 H2SO4 solution: 1.8 mL; ② amount of 3×10-4mol·L-1 aniline blue solution: 1.5 mL; ③ amount of 0.02 mol·L-1 potassium bromate solution: 1.1 mL; ④ temperature of reaction: 30 ℃. The linearity were in the ranges of 0.01-0.2 mg·L-1 and 0.2-1.0 mg·L-1 with detection limit (3s/k) of 4.6×10-6g·L-1. The proposed method was applied to the analysis of water sample, giving values of recovery and RSD′s (n=6) in the ranges of 96.0%-104% and 1.6%-2.3% respectively.