AMPEROMETRIC RESPONSE OF ELECTRODES WITH POROUS COATINGS TO GAUSSIAN CONCENTRATION PROFILES IN FLOWING STREAMS

A numerical simulation is performed to calculate the amperometric response for a porous coating on an electrode surface to a Gaussian concentration plug in a flowing stream. The amperometric response is considered as a function of the layer thickness, the diffusion coefficient of the analyte through the layer, and the width of the Gaussian concentration profile. We consider the effect of the first two parameters on the magnitude of the current response and the lag time, which is the time delay between the time at which the peak of the concentration profile reaches the outer edge of the porous layer and the time of the peak current response. However, although it is not possible to decouple the magnitudes of the layer thickness and the diffusion coefficients from experimental measurements, it is possible to determine one parameter if the other is known. The width of the amperometric response varies linearly with that of the incident Gaussian concentration profile.