Ion-selective electrode for the determination of some multidrug resistance reversers

Several plasticized poly(vinyl chloride) (PVC) membranes of different compositions were tested for use in the construction of an ion-selective electrode for the determination of some multidrug resistance reversers. A membrane with a 1:2 (w/w) 2-nitrophenyl octyl ether to PVC ratio, doped with 1% (w/w) tetrabutylammonium tetraphenylborate was selected. In the experimental conditions selected, a linear relationship between potential and log c was obtained between 1 × 10−5 and 1 × 10−2 mol l−1 chlorpromazine, clomipramine, imipramine, desipramine and verapamil with an almost Nernstian response. Good repeatability and reproducibility were obtained. The electrode proposed was applied satisfactorily to the determination of chlorpromazine, clomipramine, imipramine and verapamil in pharmaceuticals.