Modified graphites: application to the development of enzyme-based amperometric biosensors

For a series of graphite electrodes, modified with microquantities of Pd+Pt mixture in varied proportions, surface morphology of the catalytically active phase was studied with scanning electron microscopy (SEM), while the catalytic activity was examined at electrochemical reduction of hydrogen peroxide by means of steady-state polarization curves and constant potential amperometry. It was proven that the graphite, exhibiting the highest electrocatalytic activity (modified with Pd+Pt mixed in the ratio 70%:30% at t(deposit)=10 s) is distinguished with the smallest average size of the microformations. The operational characteristics of the same electrode and graphite modified with microquantities of Pd+Au mixed in the same ratio (70%:30%; t(deposit)=10 s) were compared. The application of these electrodes as basic transducers in highly selective biosensors for glucose and xanthine was demonstrated.