Simultaneous analysis of multiple bioactive constituents in Rheum tanguticum Maxim. ex Balf. by high-performance liquid chromatography coupled to tandem mass spectrometry

A simple, rapid method was developed using on-line high-performance liquid chromatography (HPLC)-diode array detection (DAD)/electrospray ionization mass spectrometry (ESI-MS) to simultaneously analyze multiple bioactive constituents in the extract of Rheum tanguticum Maxim. ex Balf. (Dahuang), a traditional Chinese medicine (TCM). Many bioactive constituents gave prominent M-H]- ions in the negative ion ESI mass spectra. Among them, 41 different constituents including 16 anthraquinone derivatives, 7 phenylbutanone glucopyranosides, 4 stilbenes and 14 tannins were unambiguously identified or tentatively characterized based on their retention times, UV spectra and mass spectra in comparison with the data from standards or references. Meanwhile, some principles of fragmentation behavior for different types of constituents were proposed, which could contribute to the elucidation of these constituents in Rheum tanguticum.