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 statio nary phase was modified with polyaniline or polypyrrole film to add se lectivity to the separation. At negative stationary phase potentials a t 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 res ult of the formation of cationic sites in the film. Halide ions were s eparated successfully at 0.3 V, although carboxylic anions eluted exha ustively from the column with the least potential dependence of all th e ions studied. When oxidatively treated carbon particles were used wi th polyaniline, an increase in retention time started at a potential m uch more negative than that at which film oxidation was observed. When the stationary phase was modified with polypyrrole, anions were irrev ersibly taken up in the film, and the anions inserted could be eluted after a negative potential perturbation.