NOVEL ELECTROANALYTICAL METHOD BASED ON R EDOX MEDIATOR MODIFIED CARBON ELECTRODES

Chemically modified electrodes are often employed as sensing element i n biosensors. In these cases, usually amperometric detection is applie d. In this work chemically modified electrodes were prepared by adsorb ing benzophenoxazin-type redox mediator molecules on the surface of an electrochemically pre-treated glassy carbon electrode. A special elec trochemical signal-generating method was worked out for biosensors. Us ing the method, in the initial period, a short (1-10 sec) controlled p otential step is employed. After this the potential control is discont inued and the change in 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 in a well-defined correl ation with the concentration of the species to be measured. The NADH r edox coenzyme was used as a model analyte compound. A computer-control led apparatus and the necessary measurement and evaluation programs we re developed and used in the measurements. In the paper the basic prin ciples of the technique, the construction of the apparatus as well as some preliminary experimental results are summarised.