Development of novel chemical sensors is closely related to the development of new materials for both molecular recognition and signal transduction. Potentiometric ion sensors based on conducting polymers are relatively new types of chemical sensors. Conjugated polymers are useful as transducers in chemical sensors. One of the key issues is to combine conjugated polymer transducers with selective molecular recognition in order to obtain durable chemical Sensors [1]. Present research describes the preparation and the performance of polypyrrole film doped with anionic chromotropic acid as a solid state potentiometric sensor for Cr(VI). Polypyrrole (PPY) films were obtained on different substrates by anodic electropolymerization using chromotropic acid disodium salt (CHR) as an anionic dopant. The deposition of PPY film has been performed by the means of cyclic voltammetry. The effect of polymerization condition on the characteristics of potential response of the sensor towards Cr(VI) was investigated. The concentration of pyrrole and CHR, the electrode substrate, the number of voltammetric cycles and pH were optimized. Under the optimized conditions, the proposed sensor works satisfactory in the concentration range of 10-4 to 10-1 mol L-1 of chromate ion with a slope of 29.8 mV decade-1 and a fast response time of 30 s. The developed sensor has been applied for the potentiometric determination of chromate in industrial wastewater samples.

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