Belladonna alkaloids and phenobarbital combination pharmaceuticals analysis I: High-performance liquid chromatographic determinations of hyoscyamine-atropine and scopolamine.

High-performance liquid chromatographic separations are described for the analysis of hyoscyamine-atropine and scopolamine in combination pharmaceutical dosage forms containing phenobarbital. A mobile phase containing 0.034 M tetramethylammonium phosphate in water-methanol (21:10, pH 2.0) separated hyoscyamine or atropine from scopolamine on an octadecylsilane column in less than 9 min. Monitoring of the column effluent at 220 nm gave a detection limit of 0.02 microgram for each alkaloid. Hyoscyamine sulfate and/or atropine sulfate were determined as total equivalent hyoscyamine sulfate, and scopolamine hydrobromide was determined as a separate entity. Data from the application of the method to commercial pharmaceutical products are also presented.