Cyclic voltammetric studies of copper and manganese in the presence of L-leucine using glassy carbon electrode

Abstract

Cyclic voltammetric studies were used to investigate the interaction behavior of the metal ions such as Cu(II) and Mn(II) with L-leucine. The interaction studies have been carried out in variation of metal ion concentration, leucine concentration, pH and scan rate. The results indicated that Cu(II)/Cu(I) and Mn(I)/Mn(0) were reversible but Cu(I)/Cu(0) and Mn(II)/Mn(I) were quasireversible. Moreover, the results indicated that both the cathodic and anodic peaks were shifted and developed new peaks upon the addition of the leucine. The development of the new peaks suggested the formation of metal-leucine complex. The intensities of the new peaks were increased with increasing both the concentrations of metal ions as well as leucine. This is due to the formation of more metal-leucine complex that enhanced the peak intensities. The increasing trend of the peak intensities of the metal-leucine complex as a function of pH is due to the formation of more metal-leucine complex. This is because the coordination sites of the leucine molecules were increased with increasing pH that favored the formation of more metal-leucine complex. The intensities of the peak current were also increased with increasing scan rate that has been explained by the Randles-Sevcik equation. The voltammograms for both the metal ions showed two pairs of signals for both the cathodic and anodic modes and every step was single electron process. A linear behavior of ip vs. 1/2 plot indicated that the electrochemical processes were diffusion controlled.