ELECTROCHEMISTRY OF CONDUCTIVE POLYMERS-X - POLYANILINE-BASED POTENTIOMETRIC SENSOR FOR DISSOLVED-OXYGEN

A platinum electrode coated with polyaniline (PA) was examined as a potentiometric or an optical sensor for dissolved oxygen, and the results are reported. While the polymer-modified electrode behaved satisfactorily as a potentiometric sensor, its optical response (i.e., absorbance) gave a narrow linear region for varied oxygen concentrations. This conducting polymer-coated electrode was characterized to give approximately 97 mV/decade of the oxygen concentration and a voltage signal range of about 400 mV, representing at least three orders of magnitudes of dynamic linearity over the dissolved oxygen concentration. The potentiometric sensing electrode showed reasonably short response times, excellent reproducibility, and good stability. A detection limit of about 5 x 10(-7) mol/L of dissolved oxygen was estimated from the potentiometric response of PA-coated electrodes.