Electrochemistry of White Wine Polyphenols Using PEDOT Modified Electrodes

The conducting polymer PEDOT (poly-3,4-ethylenedioxythiophene) has been polymerized onto 3 mm and 10 μm electrodes from a propylene carbonate solution. The electrodes have then been tested in a Chardonnay wine, including dilutions in a model wine solution, with comparisons made to scans with a glassy carbon electrode. A well-defined oxidation peak was obtained for the white wine at PEDOT in the 400 to 450 mV (Ag/AgCl) range, where peaks were also obtained for the representative phenolics caffeic acid and catechin. The voltammetry at PEDOT was typical of a surface-confined process. Significant preconcentration, leading to an increased current response, was noted over a period of 20 min of holding time. Extensive PEDOT growth was observed in the microelectrode case, leading to current densities for the oxidation of caffeic acid over 1000 times greater than those observed at the macroelectrode, matching the high surface area and fractal-type growth observed in SEM images.