Reductimetric determination of thiazine dyes with iron(II)

Abstract

A simple and convenient reductimetric titration method has been developed for the determination of thiazine dyes employing iron(II) as a new reductant in buffer medium and in the presence of oxalate. The <i>p</i>H range and oxalate ion concentrations of the medium for rapid reduction of the dyes with iron(II) are 3.0-4.0 and 0.06-0.12 <i>M</i> respectively. In these titrations all the dyes are reduced to their colourless leuco-bases in a two-electron reduction. A more extensive study on the redox potentials of iron(III)/iron(II) couple in buffer medium of different <i>p</i>H and oxalate ion concentrations has been carried out.