Qualitative and quantitative characterization of chemical constituents in Xin-Ke-Shu preparations by liquid chromatography coupled with a LTQ Orbitrap mass spectrometer.

Xin-Ke-Shu (XKS), a traditional Chinese medicine (TCM) preparation containing five herbal medicines, has been commonly used for the treatment of coronary heart disease in China. However, the chemical constituents in XKS have not been clarified yet. In order to quickly define the chemical profiles and control the quality of XKS preparations, liquid chromatography coupled with electrospray ionization hybrid linear trap quadrupole orbitrap (LC-LTQ-Orbitrap) mass spectrometry was applied for simultaneous identification and quantification of multi-constituent. A total of 51 compounds, including phenolic acids, isoflavone-C-glycosides, isoflavone-O-glycosides, flavonoids, and triterpenoid saponins, were identified or tentatively deduced on the base of their retention behaviors, MS and MS(n) data, or by comparing with reference substances and literatures. In addition, an optimized LC-ESI-MS method was established for quantitative determination of 15 marker compounds in XKS preparations from 7 independent pharmaceutical companies. The validation of the method, including spike recoveries, linearity, sensitivity (LOD and LOQ), precision, and repeatability, was carried out and demonstrated to be satisfied the requirements of quantitative analysis. This is the first report on the comprehensive determination of chemical constituents in XKS preparations by LC-LTQ-Orbitrap mass spectrometry. The results suggested that the established methods would be a powerful and reliable analytical tool for the characterization of multi-constituent in complex chemical system and quality control of TCM preparations.