Simultaneous Electrochemical Determination of Diffusion and Partition Coefficients of Potassium Ferrocyanide for Albumin-Glutaraldehyde Membranes

摘要

The determination of true diffusion and partition coefficients for the transport of electroactive materials through membranes consisting of enxymes of immunocompounds immobolized on electrode surfaces is an important topic in biosensor development. Both 1) Chronoamperometry with a stationary electrode and 2) steady-state diffusion limited current measurements with a rotating disk electrode can be used indpendently to obtain diffusion coefficients for membranes attached to electrodes. The effective diffusion coefficient is based on the true diffusion coefficient and the equilibrium partition coefficient. This paper describes a sequential procedure in which potential step chronoamperometry is followed by limiting current rotating electrode measurements. The method was applied to the transport of potassium ferrocyanide through an albumin-glutaraldehyde cross-linked membrane coating on a platinum electrode. The resulting data was used to calculate both the true diffusion and the partition coefficients without the need for additiona measurements. The coefficients were influences strongly by the pH of the electrolyte. (Reprints)