| Abstract [eng] |
Amperometric responses of hydrogen peroxide, ascorbate and paracetamol have been studied at platinum electrodes coated with Nafion or electropolymerized polypyrrole and poly(o-phenylenediamine) and polyaniline (PANI) layers. Among the three layers studied, the Nafion layer shows superior properties. It possesses high permeability to hydrogen peroxide (95% as compared to naked platinum) and drastically diminishes responses from common interferences like ascorbate (up to 1–4%) and paracetamol (up to 46%). The electropolymerized poly(o-phenylenediamine) layer also shows good permeability to peroxide (90%), whereas its ability to repel ascorbate (up to 11–46%) does not appear to be as efficient as that of Nafion. The electropolymerized polypyrrole layer retards the permeability of peroxide and paracetamol up to 60% and increases the response to ascorbate by the factor of 1.9–2.6, probably due to its electrocatalytic action. Platinum electrodes covered with the films of electropolymerized PANI display reduced response both to hydrogen peroxide and paracetamol, depending on the thickness of the film. Ascorbate, in contrast, causes an increase in current due to the electrocatalytic nature of this process. It is concluded that PANI coatings do not warrant an adequate discrimination between the analytes studied. |
