Catalytic determination of nanogram amounts of FE(II, III) by the oxidative coupling reaction of N-pheniyl-p-phenylenediamine with N,N-Dimethylaniline

A catalytic method for the determination of Fe(II, III) is proposed. The method is based on the catalytic effect of Fe(III) on the color reaction ofN-phenyl-p-phenylenediamine withN,N-dimethyl-aniline in the presence of hydrogen peroxide. Fe(II) is also determined, being oxidized by hydrogen peroxide. Acetate acts as an activator for the catalytic effect of Fe(III). As little as 10−8M of Fe(II, III) can be determined by measuring the absorbance of the reaction product (λmax=728 nm) at a fixed time after the initiation of the reaction. The method is usefull for the determination of iron in various water samples.