Spectrophotometric Determination of Aromatic Amines

A method for spectrophotometric determination of four aromatic amines is described. The method is based on the reaction between the amine and the colorless Fe(III)-ferrozine complex. The amine reduces iron from Fe(III) to Fe(II) which forms a violet colored complex with ferrozine. The method is suitable for to the determination of 1,4-phenylenediamine, 2,4-diaminotoluene, 8-aminoquinoline and 2-amino-3-hydroxypyridine. The effect of different factors such as; pH, stability of the complex, temperature, ferrozine concentration, Fe(III) concentration and methanol concentration have been studied. The composition of the complex as well as the tolerance amount of other amines have been reported. Maximum absorbance is at 562 nm and Beer's law is obeyed over the ranges 0.17–1.6 ppm for 1,4-phenylenediamine, 0.45–3.7 ppm for 2,4-diaminotoluene, 0.51–3.4 ppm for 8-aminoquinoline and 0.53–4.4 ppm for 2-amino-3-hydroxypyridine. The obtained molar absorbtivities were 4.7×10^4, 2.0×10^4, 1.6×10^4, 1.5×10^3 l mol^−1 cm^−1 respectively.