FOULING-RESISTANT, POLYMER-MODIFIED GRAPHITE-ELECTRODES

Oxidation of several biochemically important phenols (phenol and tyrosine) and methoxyphenols (homovanillic acid, eugenol, vanillin and p-methoxyphenol) at spectroscopic graphite electrodes results in deactivation or fouling of the electrode surface. As has been previously well described, fouling is often due to the build-up of the oxidation products of these compounds at the electrode surface. Electrodes coated with gamma-irradiated immobilized films of poly(N-vinylpyrrolidone) do not exhibit the decrease in response with time observed at bare electrodes during the oxidation of these compounds. In some instances, this may be due to the structure of the polymer which may prevent large amounts of oxidation products from forming. In other instances, however, the nature of the products formed may differ at the coated electrodes. In this situation, responses as high as those initially obtained at bare electrodes may be obtained without the decrease in response as a function of time associated with bare electrodes. © 1990.