A simple colorimetric method for the determination of aromatic amines

A simple colorimetric of aromatic amines was developed by using sodium nitrate in acid medium for the determination of five aromatic amines including diphenylamine (DPA), 2-aminodiphenyl (2-ADP), 4-aminodiphenyl (4-ADP), p -phenylenediamine ( p -PDA) and o -phenylenediamine ( o -PDA). The effect of various factors such as type and concentration of acid, sodium nitrate concentration and reaction temperature were inspected. Upon the optimized condition, the reaction colors of DPA, 2-ADP, 4-ADP, p -PDA and o -PDA gave blue, dark pink, red, light pink and brown, respectively. The linear range concentration of DPA, 2-ADP, 4-ADP, p -PDA and o -PDA were obtained at 1-50, 1-170, 1-20, 1-100 and 1-150 mg.L -1 whereas the detection limit were found at 0.052, 0.081, 0.054, 0.001 and 0.009 mg.L -1 , respectively.