GLC analysis of theophylline, hydroxyethyltheophylline, and diphenylpyraline hydrochloride syrup

A GLC method for determining theophylline, hydroxyethyltheophylline, and diphenylpyraline hydrochloride is presented. The method permits the separation and quantitative determination of the therapeutically active ingredients with a single injection in an overall time of approximately 2.5 hr.