COPPER DISPERSED INTO POLYANILINE FILMS AS AN AMPEROMETRIC SENSOR IN ALKALINE-SOLUTIONS OF AMINO-ACIDS AND POLYHYDRIC COMPOUNDS

A chemically modified electrode composed of copper microparticles disp ersed into a polyaniline (PANI) film was investigated as an amperometr ic sensor of scarcely electroactive compounds possessing -OH and -NH2 groups. Glassy carbon was used as an electrode material and modified f irstly by a PANI film, then allowed to stand in contact with a solutio n of copper ions, and finally, the electroreduction was done at -0.3 V . The electrochemical behaviour of the resulting modified electrode in alkaline medium was examined by cyclic voltammetry and flow-injection amperometry. Using some representative compounds, the effect of coppe r loading and pH on the electrode response was investigated. Constant- potential amperometric detection was applied in conjunction with anion -exchange chromatographic (AEC) separations of amino acids and carbohy drates. At an applied potential of 0.55 V vs. Ag/AgCl, the detection l imits (S/N=3) for all analytes investigated ranged 5-15 pmol, and the linear dynamic range was three-four orders of magnitude above the dete ction Limits. The resulting modified electrode was found to retain 95% of its initial response in flowing streams for 3 h of operating time.