Electrocatalytic study of an electrode modified with Reactive Blue 4 dye covalently immobilized on amine-functionalized silica

In the present work, we investigated the immobilization and electrochemical behavior of Reactive Blue 4 dye on 3-aminopropyl-functionalized silica. The electrochemical behavior of the modified electrode and the electro-oxidation of dipyrone were studied by cyclic voltammetry. The modified electrode showed a well-defined redox coupling with a formal potential of 0.45 V (vs. saturated calomel reference electrode) assigned to anthraquinone/anthrahydroquinone redox process (pH = 2). The modified electrode also demonstrated electrocatalytic activity and an increased peak current towards the oxidation of dipyrone at a reduced overall potential. The electrocatalytic process was found to be highly dependent on the pH of the supporting electrolyte. The voltammetric responses for dipyrone were linear in the concentration range of 49.9 to 440 μmol L−1 at a pH of 2.0 with a detection limit and sensitivity of 22.0 μmol L−1 and 0.0278 μA mmol L−1, respectively.