Electrochemical Investigations of L-Cysteine Interactions with Bismuth Ions

Abstract

The interaction of L-cysteine with various bismuth compounds, namely, bismuth(III) salicylate, bismuth(III) citrate, and bismuth(III) nitrate, was studied at pH 1.0 (0.100 M HNO3 and 0.100 M HCl) and pH 7.4 MOPS buffer by cyclic voltammetry at glassy carbon and boron-doped diamond electrodes. Using details of the voltammetric behavior, it was determined that Bi3+ and L-cysteine (Cys) form a soluble complex at both pH 1.0 and pH 7.4. In addition, the reduction of the bismuth-cysteine complex to bismuth metal results in subsequent bismuth stripping. UV-VIS spectroscopy revealed that Bi3+ and L-Cysteine form a 1:2 Bi3+: Cys complex in pH 7.4 MOPS buffer.