ELECTROCHEMICAL SEPARATION OF IONIC COMPOUNDS USING A CONDUCTIVE STATIONARY-PHASE COATED WITH POLYANILINE OR POLYPYRROLE FILM, AND ION-EXCHANGE PROPERTIES OF CONDUCTIVE POLYMERS

We report here the separation of anionic compounds using a conductive stationary phase which consists of glassy carbon particles. The stationary phase was modified with polyaniline or polypyrrole film to add selectivity to the separation. At negative stationary phase potentials at which polyaniline was in the reduced form, anions were not retained on the column. When polyaniline was oxidized at potentials above 0.1 V vs. Ag\AgCl\sat.KCl\, the retention time of anions increased as a result of the formation of cationic sites in the film. Halide ions were separated successfully at 0.3 V, although carboxylic anions eluted exhaustively from the column with the least potential dependence of all the ions studied. When oxidatively treated carbon particles were used with polyaniline, an increase in retention time started at a potential much more negative than that at which film oxidation was observed. When the stationary phase was modified with polypyrrole, anions were irreversibly taken up in the film, and the anions inserted could be eluted after a negative potential perturbation.