title: Nuclear magnetic resonance analysis of pharmaceuticals-VII Determination of aminophylline in tablets.
abstract: An NMR procedure is described by which theophylline and ethylenediamine are simultaneously determined in aminophylline tablets. t-Butyl alcohol was chosen as the internal standard and 4% ammonia-0.3% potassium cyanide in deuterium oxide was the solvent. The solvent system was selected to deal with the problems of solubility of the theophylline, overlapping of the components' resonance signals, and potential interference from metal impurities. Known standard and commercial preparations were determined and the results compared with those obtained by alternative procedures. The technique, when applied to the determination of aminophylline in tablets, is rapid, simple and specific and has an error of 1-2%.
authors.affiliation: Food and Drug Administration, U.S. Department of Health, Education and Welfare, 850 Third Avenue, Brooklyn, New York 11232, U.S.A.
authors.forename: J W
authors.initials: JW
authors.lastname: Turczan
authors.forename: B A
authors.initials: BA
authors.lastname: Goldwitz
authors.forename: J J
authors.initials: JJ
authors.lastname: Nelson