A Facile Spectrophotometric Determination of Nitrite Using Diazotization with p-Nitroaniline and Coupling with Acetyl Acetone

Abstract.

 A simple and sensitive spectrophotometric method is described for the determination of nitrite in water and soil samples. The method is based on the reaction of nitrite with p-nitroaniline to form a diazonium ion, which is coupled with a new coupling agent, acetyl acetone in an alkaline medium. The dye shows an absorption maximum at 490 nm and obeys Beer’s law over a range of 0.5 to 14 µg nitrite per 10 mL analyte. The molar absorptivity of the colour system is 3.2×10⁴ L mol⁻¹ cm⁻¹. The relative standard deviation is 2.7% (n = 10). The dye formed is stable for 3 h. The effect of interfering ions on the determination is described. The method has been suggested for the determination of nitrite in water and soil samples. The results obtained were compared with the standard N-(1-naphthyl) ethylenediamine dihydrochloride method.