[Study and spectrophotometric determination of nitrite with sulfanilamide and N-phenyl J-Acid system]

In the present article, compounds used in diazotizing-coupling reaction were selected. The conditions and methods of diazotizing-coupling chromogenic reaction were studied. A new method of diazotizing-coupling spectrophotometry with sulfanilamide(p-aminobenzene sulfonamide) and J-Acid series dye intermediates (N-phenyl J-Acid, J-Acid, Di-J-Acid) to determine nitrite was developed. At room temperature, in the presence of potassium bromide, nitrous acid reacted with sulfanilamide in the medium of thin hydrochloric acid. Then diazonium salt reacted with N-phenyl J-Acid in the aqueous solution of sodium carbonate, forming coloured azo compounds. The apparent molar absorptivity was 4.63 x 10(4) L x mol(-1) x cm(-1). The Beer's law was obeyed in the range of 0.003-0.7 mg x L(-1). The recoveries were in the range of 99.5%-101.6%. RSD was 2.1%. This method has been used for the determination of trace nitrite in the environmental water.