THE EFFECT OF THE NATURE OF THE POLYMER BACKBONE ON THE STABILITY AND THE ANALYTICAL RESPONSE OF POLYMER-MODIFIED ELECTRODES

The synthesis, characterization, and sensor application of the novel redox polymer [Os(bipy)(2)(PS)(7.5)(DMAP)(2.5)Cl]Cl, where bipy = 2, 2'-bipyridyl, PS = polystyrene, and DMAP = poly[4-(N-methyl-N-p-vinylbenzylamino) pyridine], are described. The charge transport properties of electrodes modified with the redox material are investigated using cyclic voltammetry and chronoamperometry. The modified electrode behaves as an efficient electrocatalyst for the outer-sphere reduction of Fe-III, with the cross-exchange reaction occurring at the surface of the polymer (Sk'') at concentrations less than 1.0 x 10(-3) mol dm(-3) Fe-III, with a change over to the St(e) kinetic regime at higher substrate concentrations. Direct agreement was observed between the kinetic behavior at rotating disk electrodes and in thin-layer flow cells. Application of the modified electrodes for the determination of iron in pharmaceutical formulations and the long term stability of the electrodes are investigated. The results obtained are compared with those reported for the analogous metallopolymer [Os(bipy)(2)(PVP)(10)Cl]Cl, where PVP is poly-4-vinylpyridine.