Characterization of an unknown component in Noscapine using liquid chromatography–mass spectrometry and proton nuclear magnetic resonance spectroscopy

Analytical and semipreparative LC methods were used to quantitate and isolate an unknown component (Impurity A) found in samples of bulk Noscapine. This component was also examined by LC–ESI-MS and 1H-NMR. It was concluded that the structure of Impurity A only differed from Noscapine in that it possessed a hydroxyl group at position 21 of the isobenzofuranone moiety.