Kinetic-catalytic determination of traces of iron by the oxidative coupling reaction of 3-methyl-2-benzothiazolinone hydrazone with N,N-dimethylaniline

摘要

A new kinetic-catalytic method by the initial rate procedure for the determination of nanogram level of iron(III) is developed, which is based on its catalytic effect on the oxidative coupling of 3-methyl-2-benzothiazolinone hydrazone (MBTH) with N,N-dimethylaniline (DMA) to form an indamine dye (λ_(max) = 590 nm) in the presence of hydrogen peroxide. Iron(II) is also determined, being oxidized to iron(III) by hydrogen peroxide. Calibration graphs obtained by the initial rate method are linear in the range 1-1000 ng ml~(-1) Fe and as low as 10~（-8） M Fe(II, III) can easily be determined. The relative standard deviations are 6.6, 2.5 and 1.5% for ten determinations of 1, 20 and 60 ng ml~(-1) of Fe(III), respectively. The method is applicable to the determination of iron in natural waters without preconcentration and separation.