A new strategy for simultaneous determination of cysteamine in the presence of high concentration of tryptophan using vinylferrocene-modified multiwall carbon nanotubes paste electrode

The electro-oxidation of cysteamine (CA) and tryptophan (TP) were studied by vinylferrocene-modified carbon nanotubes paste electrode using cyclic voltammetry, chronoamperometry, electrochemical impedance spectroscopy, and square wave voltammetry. This modified electrode exhibits persistent electron-mediating behavior followed by well-separated oxidation peaks towards CA and TP with decreasing their overpotentials. For the mixture containing CA and TP, the peaks potential well separated from each other. Using the modified electrode, the kinetics of CA electrooxidation was considerably enhanced by lowering the anodic overpotential through a catalytic fashion. Using square wave voltammetry, simultaneous determination of AC and TP has been explored at the modified electrode. Their square wave voltammetrics peaks current increased linearly with their concentration at the ranges of 0.09-500 and 5.0-1,000 mu M, respectively with the detection limits of 0.05 and 1.0 mu M, respectively. The modified electrode was successfully used for the determination of the analytes in real samples with satisfactory results.