Layer-by-layer thin film-coated electrodes for electrocatalytic determination of ascorbic acid

Multilayer thin films composed of poly(allylamine hydrochloride) (PAH) and carboxymethyl cellulose (CMC) have been prepared on the surface of a gold (Au) disk electrode by a layer-by-layer deposition of PAH and CMC and ferricyanide ions ([Fe(CN)6]3−) were confined in the film. [Fe(CN)6]3− ions can be successfully confined in the films from weakly acidic or neutral [Fe(CN)6]3− solutions, while, in basic solution, [Fe(CN)6]3− ion was not confined. The [Fe(CN)6]3− ion-confined Au electrode showed clear redox peaks in the cyclic voltammogram around 0.35 V versus Ag/AgCl. The amounts of [Fe(CN)6]3− ions confined in the films depended on the thickness of the films or the number of layers in the LbL films. The [Fe(CN)6]3− ion-confined Au electrode was used for electrocatalytic determination of ascorbic acid in the concentration range of 1–50 mM.