The potentiometric response of chemically modified electrodes

The electrochemical polymerization of ortho-methoxyaniline and ortho-methylaniline was studied on platinum electrodes. The electrochemical response of electropolymerized films exhibits three well-defined redox processes similar to those observed for polyaniline. The potentiometric response of these electrodes was analyzed, and the polymeric film prepared with ortho-methylaniline showed a better response as a pH sensor than that prepared with ortho-methoxyaniline. The electrode prepared with poly(ortho-methylaniline) showed an apparent Nernstian response in a 1–12 pH range with a slope of 63.8 mV/ decade, while the linear range of the electrode prepared by poly(ortho-methoxyaniline) exhibited a linear relationship in the 2–11 pH range with a slope of 62.0 mV/decade.