A stability-indicating proton nuclear magnetic resonance spectroscopic method for the analysis of propantheline bromide in pharmaceutical samples

A rapid, specific and accurate proton nuclear magnetic resonance (H-1 NMR) spectroscopic method was developed for the simultaneous quantitative analys is of propantheline bromide and its degradation product, xanthanoic acid, i n bulk materials and tablets. 1,3,5-Trinitrobenzene served as an internal s tandard and deuterochloroform was used as the solvent for the analytical sa mples. The quantities of propantheline bromide and xanthanoic acid were cal culated on the basis of the integrals for signals of the methine proton of propantheline at 5.09 ppm, the methine proton of xanthanoic acid at 4.99 pp m, and the aromatic protons of the internal standard at 9.39 ppm. The accur acy of the method was established through the analysis of synthetic mixture s containing the parent compound, its degradation product and the internal standard. An excellent agreement was verified between the assay results and the quantities of the various compounds in the mixtures. The mean SID reco very values for propantheline bromide and xanthanoic acid from a set of 10 synthetic mixtures were 99.6 +/- 0.8% and 98.9 +/- 1.8%, respectively. The assay of 10 lots of commercial propantheline bromide tablets by H-1 NMR spe ctroscopy indicated drug and degradate contents in the ranges 97.1-99.8% an d 0.1-0.9%, respectively. In addition, the proposed analytical method was f ound suitable for detecting the formation of xanthanoic acid from propanthe line bromide in aqueous media in concentrations below 0.1% of that of the p arent compound.