KINETIC SPECTROPHOTOMETRIC DETERMINATION OF NITRITE BASED ON ITS CATALYTIC EFFECT ON THE OXIDATION OF CELESTINE BLUE BY BROMATE

A kinetic catalytic method for the determination of nitrite in water samples is described. In acidic solution, Celestine Blue (CB) is oxidized by bromate to form a colorless compound. The reaction is accelerated by trace amounts of nitrite and can be followed by measuring the absorbance at 545 nm. The reaction is monitored spectrophotometrically by measuring decrease in absorbance by fixed time method. The change in absorbance, observed for every 5 minutes was utilized as an analytical signal. Under the optimum experimental conditions of 1 mol.dm-3 sulfuric acid, 2.75× 10-4 mol.dm-3 CB, 1.2×10-3 mol.dm-3 bromate, and 4.3×10-5 mol.dm-3 nitrite. The detection limit was found to be in the range of 4.3×10-5 to 4.3×10-6 mol.dm-3 of nitrite. By using this method the amount of nitrite present in natural river water, tap water, sausage samples and waste water samples was determined.