LIQUID-CHROMATOGRAPHIC DETERMINATION OF SCOPOLAMINE, HYOSCYAMINE, ANDPHENOBARBITAL IN TABLETS

A liquid chromatographic method using a reversed-phase C-18 column and octanesulfonic acid sodium salt-methanol as the mobile phase was deve loped for the simultaneous determination of phenobarbital, scopolamine , and hyoscyamine in tablets, The mixture of the 3 drugs was resolved in <8 min, Detector responses were linear for 10 mu L injections of th e following: scopolamine hydrobromide, 8.25-206.3 mu g/mL; hyoscyamine sulfate, 15.01-750.76 mu g/mL; and phenobarbital, 250-751 mu g/mL, Re coveries from tablets were 100.8% for scopolamine hydrobromide, 100.1% for hyoscyamine sulfate, and 100.3% for phenobarbital. Replicate inje ctions of scopolamine hydrobromide, hyoscyamine sulfate, and phenobarb ital gave an overall relative standard deviation of <1.0% (n = 10), Th e method detected as little as 3.3 ng scopolamine hydrobromide.