POLYMERIC MEMBRANE ION-SELECTIVE ELECTRODES TO CERTAIN TYPES OF DRUGS

The construction and performance of ion-selective membrane electrode for neuroleptic tranquilizers by coating a graphite rod with a film of polyvinylchloride plasticized with a mixture of dioctylphtalate-nitrobenzene and incorporated by the phosphotungstate as counter-ion is described. The electrode exhibites a Nernstian response in the range of pH 3 to 4 for the fluphenazine, between pH 3.5 to 5.5 for the methixene and pH 5.1 to 6.3 for the dibenzepine. The ion-selective electrode slopes were into the range 53-55 mV per concentration decade over 10(-3) - 10(-6) M. Selectivity coefficients were determined for organic substances containing the pyrrolidin, piperazin and piperidin. Dibenzo compounds present a certain degree of interferences but the benzodiazepins family do not interfere. Direct potentiometry is used to determine these compounds in pharmaceutical preparation with accurate results.