Role of carbonyl sites in the electrochemical response of 2,6-diaminopurin-8-ol

Modified graphite electrodes were prepared with materials containing carbonyl functional groups, including polypyrrole containing poly(methyl vinyl ketone). The effect of the modification on the electrochemical response of 2,6-diaminopurin-8-ol, a small, electrochemically fast biological molecule with primary amine groups which absorbs on active graphite, was evaluated. The results show that the chemical interactions between 2,6-diaminopurin-8-ol and the surface carbonyl functional groups do not by themselves contribute to the reactivity of the probe molecule.     

Scanning electron microscopy in the analysis of the activity of graphite electrodes

Copper deposition patterns on graphite electrodes were analyzed by scanning electron microscopy. The deposition patterns correlate very well with the electrochemical activity of different graphites. The results indicate that treatment of graphite by electroactivation, laser irradiation of polishing on 600-grit silicon carbide paper produces active sites on the surface. The density of the sites directly reflects the electrochemical reactivity of the surface.     

Anion-excluding polypyrrole films

A new method for modifying polypyrrole films is described. It involves complete oxidation of the film. The film produced is electronically non-conductive but ionically conductive, and has ion-selective properties based on the exclusion of anionic species. The effective pH within the film can be controlled by the choice of supporting electrolyte used during the oxidative treatment, without loss of selectivity. Cyclic voltammetry is used to demonstrate the effect of film pH on the rate of dopamine oxidation in a neutral supporting electrolyte.