Highly Selective and Reproducible Electrochemical Sensing of Ascorbic Acid Through a Conductive Polymer Coated Electrode

Abstract

The surface of an Au-disc electrode was modified through electro polymerization of aniline, in the presence of dodecyl benzene sulphonic acid (DBSA) and sulphuric acid (H2SO4) solution. The polymerization conditions were pre-optimized so that micelle formation and solution coagulation could be minimized and surfactant doped polyaniline film could be obtained through a quick, simple and one step polymerization route. The synthesized material was characterized via Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and cyclic voltammetry (CV). The effective surface area of the Au-disc, calculated through cyclic voltammetry, was immensely increased through a polyaniline (PANI) coating (0.04 and 0.11 cm2 for bare and PANI coated gold respectively). The modified electrode was utilized for ascorbic acid (AA) sensing. The changing pH of electrolyte and scan rate influenced the PANI electrode response towards AA. The modified electrode was highly selective towards AA oxidation and showed a very low limit of detection i.e. 0.0267 μmol·L–1. Moreover, the PANI coating greatly reduced the sensing potential for AA by a value of around 140 mV when compared to that on a bare gold electrode.