A method is described for the determination of nortriptyline in sugar-coated tablets. Nortriptyline is extracted into dilute aqueous hydrochloric acid containing triflupromazine hydrochloride as an internal standard. The acidic extract is then chromatographed by a reversed-phase separation using a basic solvent system in conjunction with a phenyl Corasil column.

The main advantages of the method are the simple extraction, the over-all speed of analysis and the degree of precision obtained. The method has been used to monitor the stability of experimental formulations and could readily be modified for the assay of single tablets.