Solid-State valproate ion selective sensor based on conducting polypyrrole films for determination of valproate in pharmaceutical preparations

Valproate-doped polypyrrole (PPy-val) was prepared electrochemically by anodic polymerization of pyrrole in the presence of valproate ion in an aqueous solution and was used as a valproate ion selective sensor. Polymerization was investigated under a pulse galvanostatic method. The effect of polymerization conditions on the characteristics of the potential response of the sensor was also discussed. The concentration of pyrrole and valproate ions, the electrode type, the solvent effect, and the current, time and number of pulses were optimized with the time method. The solid-state PPy-val sensor, prepared by electropolymerization of pyrrole in the presence of valproate ions on the platinum rod, showed a quasi Nernstian behavior over 4 x 10(-5)-4 X 10(-2) M Val(-) with a detection limit of 1 x 10(-5) M in an aqueous solution. The response time of the electrode was about 20 s and the electrode could be used at least for 4 months without any divergence. The potential response of the electrode was reproducible in the range pH 2-11 and was not affected by pH between 4 and 7.5. Selectivity of the sensor over diverse epileptic drugs (carbamazepine, phenobarbital and phenytoin) and inorganic salts was evaluated. The drug sensor was applied for determination of valporate ions in pharmaceutical preparations by using titration potentiometry. (c) 2005 Published by Elsevier B.V.