Applying immittance spectroscopy to monitoring hydrogen peroxide in the presence of ascorbic acid. Part I: Theoretical considerations

The theoretical prospect of utilizing AC immittance characterization of an electrochemical system to tailor the response for the selective amperometri c monitoring of a kinetically less-favored analyte in the presence of a kin etically more-favored species is explored. The selective measurement of hyd rogen peroxide in the presence of ascorbic acid is considered as a model ca se and an AC immittance model is developed from a first-principles approach based upon the partial differential equations governing transport and the kinetics of the electron transfers. The influence of various system paramet ers on the AC immittance spectra an investigated to identify the measuremen t conditions whereby the AC signal from hydrogen peroxide oxidation will be significantly larger than the AC signal from ascorbic acid.