Ion-exchange voltammetry as a solid-phase microextraction analytical method: Factors influencing the mass transfer to perfluorosulfonated ionomer film-coated electrodes and some of their consequences on the current responses

A simple theoretical model of mass transfer kinetics at an electrode coated with an ion-exchange film polymer is proposed. The model takes into account the analyte depletion in solution and gives the relationship between the ion-exchange voltammetric (IEV) peak current and the initial analyte concentration in the sample matrix. The verification of the model is investigated at disposable Nafion film-coated screen-printed electrodes, using the redox cationic (ferrocenylmethyl)trimethylammonium salt. It is shown that the theoretical model and the experimental data fit satisfactorily insofar as the variation of the extraction and apparent diffusion coefficients of the salt with the film thickness are taken into account. Indeed, the film thickness plays a crucial role for the optimization of the IEV sensitivity, because the physicochemical properties of the recast Nafion polymer are dependent on the amount per unit area of Nafion deposited on the electrode surface.