A Spectrophotometric Method for the Determination of Nitrite and Nitrate

A simple, rapid spectrophotometric method for the determination of nitrite and nitrate in water, tablets and water samples have been developed. Determination of nitrite is based on the reactions involving sulfanilic acid with methyl anthranilate as the coupling agents and determination of nitrate is based on their reduction to nitrite in the presence of Zn/NaCl. The produced nitrite is subsequently diazotized with sulfanilic acid then coupled with methyl anthranilate to form an azo dye which is measured at 493 nm. The method is optimized for acidity, amount of reagents required and tolerance amount of other ions. The range of linearity for sulfanilic acid-methyl anthranilate couple was found to be 0.2-8.0 µg/ml of nitrite with molar absorptivity be 1.03x10 4 Lmol -1 cm -1 and sandell ’ s sensitivity 4.5x10 -3 µg cm -2