VANADYL AND MOLYBDENYL PHTHALOCYANINES AS IONOPHORES FOR SALICYLATE-SELECTIVE MEMBRANES COATED ON GRAPHITE ELECTRODES

Abstract

Salicylate selective electrodes based on oxo(phthalocyanato)-vanadium(IV) [VO(Pc), vanadyl phthalocyanine] and oxo-(phthalocyanato)molybdenum(IV) [MoO(Pc), molybdenyl phthalocyanine] are described. The electrodes were prepared by incorporating the ionophores into plasticized poly(vinyl chloride) membranes, which were directly coated on the surface of graphite electrodes. The resulting electrodes demonstrate Nernstian responses over a wide linear range (10⁻⁷-10⁻¹M) salicylate. The electrodes have a fast response time, submicromolar detection limit, and could be used over the pH range of 6–9. The proposed sensors revealed selectivity for salicylate over a number of common inorganic and organic anions. The influence of lipophilic cationic and anionic additives on the response properties of the electrodes was investigated. Highest sensitivity and the widest linear dynamic range were observed for the electrodes in the presence of trioctylmethylammonium chloride as a lipophilic cationic additive. The electrodes were successfully applied to the determination of salicylate in pharmaceutical preparations.

Keywords:

• Potentiometry
• Salicylate determination
• Ion-selective electrodes
• Vanadyl phthalocyanine
• Molybdenyl phthalocyanine

ACKNOWLEDGMENTS

The authors express their appreciation to the University of Isfahan Research Council for financial support of this work.