[Study on C21 steroidal glycosides of Cynanchum atratum by LC-MS].

High performance liquid chromatography coupled with on-line electrospray tandem mass spectrometry (HPLC/ESI-MS/MS) was used to identify C21 steroidal glycosides in the roots of Cynanchum atratum. The structures of C21 steroidal glycosides were deduced from mass fragments features in positive and negative mode. The constituents of C. atratum were separated and detected. 7 compounds were identified by comparing their ESI-MS/MS data with the reference compounds and 2 compounds were inferred solely by the ESI-MS/MS data. The method is sensitive, and provides good separation and rapid qualitative characterization of C21 steroidal glycosides in the roots of C. atratum.