A Potentiometric Sensor for Ketoprofen Based on a β-Cyclodextrin Derivative

Thepreparation of Ag/AgCl inner electrode in the polymer layer (coated wire electrode) and glassy carbon electrodes for ketoprofen (3-benzoyl-alpha-methylbenzeneacetic acid) was described. The polymer membranes for both electrodes are based on beta-cyclodextrin derivatives. Inclusion complexes of ketoprofen with selected cyclodextrins were studied using IR spectroscopy and thermal analysis. The optimal membrane with heptakis-(2,3,6-tri-O-benzoyl)-beta-cyclodextrin was characterized by the Nernstian slope of 59.1 mV/decade over the linear range of 5 x 10(-5)-1.0 x 10(-2) M, detection limit of 1.2 x 10(-5) M, and response time of 10 s. It can be used in the pH range of 5.0-9.0 for 24 months without any considerable deterioration. Incorporation of beta-cyclodextrins improved the electrode s7ensitivity, limit of detection, and selectivity toward ketoprofen ions from several inorganic and organic interfering ions due to non-covalent interactions (host molecule-guest molecule). The attractive qualities of the ketoprofen sensor are low cost, comfortable application for 3-benzoyl-alpha-methylbenzeneacetic acid determination in pharmaceuticals with good precision and accuracy.