Isolation, identification and characterization of degradant impurities in Tolterodine tartrate formulation.

During the stability study of Tolterodine tartrate drug product, two unknown impurities (Impurities I and II) were detected by ultra performance liquid chromatography (UPLC). Both impurities were isolated by preparative liquid chromatography and were subjected to mass and NMR spectral studies. Based on the spectral data, the Impurities I and II were characterized as N-(3-(2-hydroxy-5-methylphenyl)-3-phenylpropyl)-N,N-diisopropyl hydroxyl ammonium trifluoro acetate and 3-(2-hydroxy-5-methylphenyl)-N-isopropyl-3-phenylpropane-1-amine oxide respectively.