Cyclic voltammetric studies of the redox behavior of iron(III)-vitamin B6 complex at carbon paste electrode

Electrochemical redox behavior of Fe-vit B-6 complex is investigated in HEPES buffer in the pH range 5.1-13.1 using cyclic voltammetry. Well-defined anodic and cathodic peaks are observed in the voltammograms at pH 13. 1. At pH 8.0, only one cathodic peak and at pH 5. 1, only one anodic peak are found. At all the pH values, the peak potential separation is much higher than that of a reversible electrochemical reaction. The peak current ratio (i(pa)/i(pc)) is less than unity and decreases with the scan rate.