Abstract
Ceramic carbon electrode modified with redox probe solution in hydrophobic polar solvent was prepared and studied. The electrode consisting of graphite powder, homogeneously dispersed in hydrophobic silicate matrix, was prepared from the mixture of methyltrimethoxysilane based sol and graphite powder by solβgel method. It was immersed in tβbutyloferrocene solution in nitrobenzene. The electrode properties were investigated by cyclic voltammetry and chronoamperometry in KNO~3~ solution of different concentration. In most cases linear polarization of the electrode towards positive potentials results in peak shaped voltammogram originating from electrooxidation of tβbutyloferrocene. Its shape changes with time, but after 5β7 scans stable curve is obtained. In all conditions the anodic to cathodic charge ratio is larger than unity. The peak current is proportional to the concentration of the redox probe in organic phase and salt in aqueous phase, whereas the midpeak potential is almost not affected by these factors. It has been concluded, that the electrooxidation of redox probe within hydrophobic silicate matrix is followed by two simultaneous processes: tβbutyloferrocenium cation transfer to the aqueous phase and anion transfer from aqueous phase. Their relative contribution depends on the ratio of concentration of the redox probe in organic phase to concentration of salt in aqueous phase.