Investigation of a novel chronopotentiometric detection method using a redox mediator modified carbon electrode

Chemically modified electrodes are often employed as sensing element in biosensors. In these cases, usually amperometric detection is employed. In this article chemically modified electrodes were prepared by adsorbing a benzophenoxazine type redox mediator molecule on the surface of an electrochemically pre-treated glassy carbon electrode. A special measurement method for electrochemical signal generation was worked out with biosensors. In this method, in the initial period, a short (1-10 s) controlled potential step is employed. After this the potential control is discontinued and the change of the electrode potential is followed in time with a zero current measuring apparatus. The rate of the potential change in a certain section of the relaxation curve is well correlated with the concentration of the species to be measured. In the paper the basic principles of the technique as well as some preliminary experimental results are summarised. In the experimental work NADH was used as a model compound.