Oxidation Mechanism of 1‐Methyl‐tryptophan and Tryptophan on Glassy Carbon Electrode: A Comparative Study

Abstract

The anodic behaviour of 1‐methyl‐tryptophan (1‐mTrp) in aqueous electrolytes was investigated on a glassy carbon electrode (GCE), using voltammetric techniques. The oxidation of 1‐mTrp was associated with an electrochemical‐chemical (EC) mechanism: one electron and one proton were removed of C2 to form an intermediate radical, 1‐mTrp⋅. This was followed by a two‐way reaction, producing a 1‐mTrp dimer and/or reaction with water to form a final hydroxylated product. The oxidation mechanism of 1‐mTrp proposed was also compared with the anodic oxidation Trp on GCE. Differential pulse voltammetry was also explored for quantification of Trp and 1‐mTrp in neutral medium with low detection limits, on an anodically pre‐treated GCE.