Spectrophotometric Determination of Nitrous Acid in the Aqueous Streams of Fast Reactor Fuel Reprocessing Using Azo Dye Method

A simple spectrophotometric method is optimized for the determination of nitrous acid in nitric acid media. This method is based on the diazotization reaction of nitrous acid with sulfanilamide and N-(1-naphthyl)-ethylene diamine dihydrochloride forming a bright pink colored azo compound. This complex is having an absorbance at 540 nm with molar extinction coefficient of 26,530 L mol cm and 16,990 L mol cm for water and nitric acid dilution, respectively; the relative standard deviation was found to be <2% and the detection limit was 1 ppm. The interference studies of nitrous acid determination with uranium and zirconium were carried out, and there is no interference in nitrous acid determination in the range of concentration studied; hence, the optimized method can be employed for the determination of nitrous acid in plant samples.