ION-TRANSFER VOLTAMMETRY OF DRUGS AT THE NITROBENZENE WATER INTERFACE/

Ion-transfer voltammetry of calcium antagonists, propranolol, and acet ylcholine were carried out by current-scan polarography with an ascend ing water electrode. The pH effect of the aqueous phase on the half-wa ve potential of the ion-transfer voltammogram was examined for each dr ug. For nicardipine, barnidipine and benidipine, the half-wave potenti al became more positive by 0.059 V per unit pH over the pH range (pH 4 -8). For propranolol, the half-wave potential became more positive by 0.059 V per unit pH at pH values above 6.8, whereas at pH values below 6.8, this potential remained constant. The half-wave potential of ace tylcholine was independent of pH at pH 5-8.5. These results could be e xplained by the E-1/2 equations of for ion transfer of drugs based on the ionization of drugs in the aqueous phase and distribution of neutr al drugs between the nitrobenzene and aqueous phases.