Electrochemical sensor for the non-enzymatic reduction of hydrogen peroxide and oxidation of gallic acid using a polyamidoblack-10B (PAB)-modified electrode

Abstract

A novel electrochemical sensor for the oxidation of gallic acid and reduction of hydrogen peroxide using a paraffin-impregnated graphite electrode modified with polyamidoblack 10B was developed. An electropolymerization method was employed for modifying the electrode surface with polyamidoblack 10B film. In order to confirm the formation of polyamidoblack 10B film on the electrode surface, the modified electrode was characterized by field emission scanning electron microscopy, attenuated total reflection infrared spectroscopy, and Raman spectroscopy analyses. The surface morphology analysis revealed sheet-like polymers – over the surface of the working electrode. The Raman and infrared spectroscopy confirmed the various functional groups and vibrational modes present in the polyamidoblack film. The electrochemical impedance spectroscopy study confirmed that the effective electron-transfer kinetics was very high due to the presence of polymer film with a very low charge-transfer resistance of 170 Ω cm⁻¹ when compared with the unmodified electrode with a high charge-transfer resistance of 4500 Ω cm⁻¹. The factors affecting the operation of the sensor, such as pH, scan rate, electrolyte, and potential, were also studied to enhance the sensitivity. The sensor exhibited excellent amperometric response in PBS pH 4 for the oxidation of gallic acid and reduction of hydrogen peroxide in PBS pH 7. The sensor showed a very wide linear range for the oxidation of gallic acid from 0.16 μM to 482 μM with a detection limit of 0.05 μM (S/N = 3) and for the reduction of hydrogen peroxide from 0.16 μM to 421 μM with a detection limit of 0.05 μM (S/N = 3), respectively. The constructed sensor is a very simple, low cost, reproducible, stable, and selective method for the determination of gallic acid and hydrogen peroxide even in real-time samples.