Collect. Czech. Chem. Commun. 1991, 56, 1833-1837

Chronopotentiometric studies of certain biologically important compounds at tubular graphite electrode

Ram Parkasha, Hari Om Guptab and Jatinder Duttb

a Department of Chemistry, Panjab University, Chandigarh 160 014, India
b Department of Chemical Engineering and Technology, Panjab University, Chandigarh 160 014, India


The chronopotentiometric studies of certain phenothiazines in hydrodynamic systems at a solution flow-through tubular graphite electrode were carried out in sulfuric acid of different concentrations. A well-defined single wave (involving 2 electrons) in 0.1M H2SO4 and two waves (involving 1 electron each) in 2.0M H2SO4 were observed. Phenothiazines are oxidized trough the formation of a monocation radical by the elimination of one electron from the lone pair of N-atom. The monocation radical is stable in sulfuric acid of a moderate concentration and is unstable in neutral or less acidic solutions. The cation radical undergoes instantaneous hydrolysis yielding sulfoxide, thus presenting an overall two-electron oxidation of the phenothiazine derivatives. The suitability of the chronopotentiometric technique for their determination was established.