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A rapid-resolution liquid chromatography (RRLC) method coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS) has been developed for analysis of oleanane-type triterpenoid saponins in Achyranthes bidentata. Collision-induced dissociation techniques were used to fragment the precursor molecular ions and the resulting product ions. A retro-Diels-Alder rearrangement from the oleanane aglycone skeleton in the MS/MS process yielded characteristic fragment ions in positive ion mode. These characteristic ions were helpful in predicting the aglycone structure. Losses of monosaccharide sequences, presence of sugar-chain fragment ions, and cleavage of CO2 were observed for important information on sugar types and attachment sequences. Fragmentation rules of three major groups of saponins from A. bidentata were summarized, and the possible fragmentation pathways were proposed. A total of 22 compounds including both the target and unknown oleanane-type triterpenoid saponins were rapidly screened and predicted in the herbal extract by the developed method. The RRLC-Q-TOF MS/MS method has provided a powerful approach for rapid separation, target screening and structural elucidation of oleanane-type saponins, and also opened perspectives for similar studies on other herbal medicines. Copyright © 2010 John Wiley & Sons, Ltd.

Here we report a rapid approach for qualitative analysis of iridoid glycosides and caffeoylquinic acids (CQAs) in Re Du Ning Injections using a Direct Analysis in Real Time (DART) ionization source coupled with quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS). In this approach, DART/MS and DART MS/MS analyses in both negative and positive ion modes were performed to characterize two iridoid glycosides and six CQAs in reference solutions and Re Du Ning Injections. Fragmentation pathways of two kinds of natural compounds were summarized. DART-MS tended to break down some labile bonds in di-CQAs. The di-CQAs yielded abundant fragment ions in the (−) mass scan spectra. Collision-induced dissociation techniques were used to fragment the precursor ions and the product ions. Moreover, differentiation of the isomers of CQAs was possible by using the relative peak abundance and characteristic ion species in MS/MS spectra. DART-MS was also employed to obtain a chemical fingerprint of Re Du Ning Injections for rapid qualitative analysis of this Chinese medicine preparation. DART/Q-TOF MS/MS has shown potential to be used as the real-time detection method for Re Du Ning Injections.