Simultaneous Investigation of Dopamine and Ascorbic Acid at Poly (Tryptophan) Modified Carbon Paste Electrode: A Cyclic Voltammetric Study

A stable modified carbon paste electrode based on the poly (tryptophan) film was prepared by electrochemical polymerization technique using cyclic voltammetry. The properties of the electrodeposited films, during preparation under different conditions and their stability were evaluated. It was found that the current response of DA and AA were greatly enhanced at this poly (tryptophan) modified carbon paste electrode. Moreover, the anodic over-potential of AA was significantly reduced for about 150 mV (vs. SCE) compared with that obtained at bare carbon paste electrode. The modified carbon paste electrode was applied to the study of electrocatalytic oxidation of DA and AA which resolved the overlapping of the anodic peaks of DA and AA in 0.1 mol L-1 acetate buffer solution at pH 6.5. The separation of the oxidation peak potentials for ascorbic acid-dopamine was about 0.277 V. Interference studies showed that the modified electrode exhibits excellent selectivity towards DA and AA.