Characterization of cobalt- and copper hexacyanoferrate-modified carbon film electrodes for redox-mediated biosensors

Cobalt and copper hexacyanoferrate films (CoHCF and CuHCF) were formed at carbon film electrodes by three different one-step processes: cycling the applied potential, application of a constant current, and chemically. All hexacyanoferrate films obtained were characterized electrochemically by cyclic voltammetry and electrochemical impedance spectroscopy. To evaluate their possible use as redox mediators for biosensors, they were applied to the determination of hydrogen peroxide in neutral phosphate buffer saline electrolyte. Chemically deposited CuHCF was found to be generally the most suitable as a mediator, although CoHCF made by potential cycling is the most useful when a very low detection limit is necessary.