THEORETICAL-STUDY OF PERMSELECTIVE LAYERS ON AMPEROMETRIC ELECTRODES IN FLOWING STREAMS

A model consisting of the response of a porous permselective coating on an electrode in an amperometric configuration is solved for two types of concentration profile impinging on the polymer solution interface. A Gaussian concentration profile and a Poisson concentration profile are examined, since both profiles typically arise in both flow injection analysis (FIA) and high-performance liquid chromatography (HPLC). Analytical expressions for current and for concentration profiles within the layer are derived. Working curves are presented that allow estimation of peak height decrease, peak broadening, lag time, and diffusional talling due to coating the amperometric detector with a permselective layer. It is possible by using these equations and working curves to estimate the diffusion coefficient of substrate through the layer and to design layers which minimize lag time and peak talling and optimize peak height.