1997 Volume 13 Issue Supplement Pages 173-176
Ion-transfer voltammetry of calcium antagonists, propranolol, and acetylcholine were carried out by current-scan polarography with an ascending water electrode. The pH effect of the aqueous phase on the half-wave potential of the ion-transfer voltammogram was examined for each drug. For nicardipine, bamidipme and benidipine, the half-wave potential became more positive by 0.059V per unit pH over the pH range (pH 4-8). For propranolol, the half-wave potential became more positive by 0.059V 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 acetylcholine was independent of pH at pH 5-8.5. These results could be explained by the E1/2 equations of for ion transfer of drugs based on the ionization of drugs in the aqueous phase and distribution of neutral drugs between the nitrobenzene and aqueous phases.