Voltammetric behavior of alizarin red S adsorbed on electrochemically pretreated glassy carbon electrodes

The electrochemical behavior of alizarin red S (dihydroxyanthraquinonesulfonate, ARS) adsorbed on electrochemically preanodized glassy carbon electrodes was studied by cyclic voltammetry. The adsorption of ARS was greatly enhanced by the electrochemical pretreatment of the electrodes. The central quinone functionalities of the adsorbed ARS underwent quasi-reversible reduction to give stable products. Oxidation of the dihydroxyl functionalities gave unstable products which underwent further follow-up chemical transformation to give new electroactive species. The products of the chemical transformation of the oxidized species could be further oxidized at a more positive potential, resulting in two pairs of quasi-reversible, quinone-like redox waves.