The oxidation of β-nicotinamide adenine dinucleotide (NADH) at poly(aniline)-coated electrodes: Part II. Kinetics of reaction at poly(aniline)–poly(styrenesulfonate) composites

Poly(aniline)–poly(styrenesulfonate) composite-coated glassy carbon electrodes are shown to produce a stable, reproducible amperometric response to NADH in citrate–phosphate buffer at pH 7. These responses have been studied as a function of electrode potential, film thickness and both NADH and NAD+ concentration. The results show that the oxidation of NADH occurs throughout the whole of the film and that NAD+, the reaction product, reversibly inhibits the reaction. Rate constants for the different processes have been obtained by kinetic modelling and compared with those previously determined for poly(aniline)–poly(vinylsulfonate) films. Preliminary comparisons imply that diffusion within ‘pores’ in these poly(aniline) composite matrices is important in determining the magnitude of the amperometric responses.