Volume 45, Number 1 (January - February 2000)

Key words:  papaverine determination, liquid membrane ion-selective electrode, pharmaceutical analysis

An ion-selective electrode with a liquid membrane selective to papaverine has been elaborated. The active membrane component is papaverine-tetraphenylborate a compound soluble in chlorobenzene. The calibration curve (E = f(log c) for papaverine is linear in the range from 1x 10^-5 to 5 x 10^-2 mol l^-1, with correlation coefficient 0.9951 and the slope of 62.6 mV/decade, which is slightly higher than Nernstian. The electrode works correctly in pH range 3.5-5.5. The membran shows good selectivity to inorganic cations and a weaker selectivity to the studied phenothiazine derivatives (promazine, chloropromazine, prometazine, thioridazine) and atropine. Determination of papaverine hydrochloride in pharmaceutical ampoules were carried out by potentiometric titration with sodium tetraphenylborate. The results agreed within 3% with the active component content declared by the manufacturer, and with paralel spectrophotometric and chromatographic determinations.