POTENTIOMETRIC RESPONSE OF ELECTROPOLYMERISED FILMS OF POLY(HYDROXYBENZENES) TO HYDRONIUM IONS

Abstract

As an alternative to the pH glass electrode, Chemically Modified Electrodes (CME) were constructed by electropolymerising poly(hydroxybenzenes) on platinum electrode. The potentiometric responses of these electrodes were analysed and the polymer film prepared with pyrogallol showed a better response as a pH sensor than that prepared with catechol or resorcinol. Effects of vanous parameters on the electropolymerisation process were investigated. Comparison with the glassy carbon electrode was also made. The CME formed under the chosen conditions gave a linear response to pH in the range 1 to 12 with a slope of -47 mV/pH and a correlation coefficient of 0.999. The pyrogallol coated platinum electrode did not show any hysteresis phenomenon. Other properties like response time an repeatability were also investigated. However, interference with a redox couple was found to occur. The sensor has fair resistance to hydrofluoric acid and can be used for potentiometric titration of hydrofluoric acid as well as other acids.