A potentiometric iodide (and other) ion sensor based on a conducting polymer film electrode: Part II. effect of electrode conditioning and regeneration techniques

A novel potentiometric halide sensor electrode for iodide, based on the entrapment of iodide/iodine/triiodide into a poly(3-methylthiophene) conducting polymer, had previously been developed using a potentiostatic technique for film formation. The effect of film thickness (with the film thickness controlled by the amount of charge passing in the electrolytic cell during the polymerization) has been studied. Also, the effects of various pre- and postconditioning parameters on the electrode performance and life time were examined and compared. The life time of the electrode was extended up to one year by storing its sensing tip in a newly designed cap. The cap consisted of two chambers linked with a special orifice; the first contained iodine adsorbed on silica or alumina and the second housed the electrode tip. The linear dynamic range of the new sensor electrode was 1 × 10−7-5 × 10−1 M iodide and the detection limit was 1 × 10−8 M iodide. The working temperature range, response time and working pH range of the electrode are 0–50°C, 1722̄0 s and 2–11, respectively. The potential for bromide, chloride, and sulfite selective electrodes based on these conducting polymer films are also presented and compared to those obtained for iodide. Moreover, the effect of changing the type of conducting polymer using poly (3-methylthiophene), poly (N-methylpyrrole) or poly (aniline) are given and compared.