Rapid separation and identification of major constituents in Pseudolarix kaempferi by ultra-performance liquid chromatography coupled with electrospray and quadrupole time-of-flight tandem mass spectrometry

A rapid and reliable method based on ultra-performance liquid chromatography (UPLC) coupled with photodiode-array detection (PDA) and electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-Q-TOF-MS/MS) has been developed for separation and identification of major constituents in extracts of root bark of Pseudolarix kaempferi Gordon (PKG). Identification of the constituents was carried out by interpretation of their retention times, UV absorption spectra, MS and MS/MS spectra, as well as the data provided by authentic standards and literatures. A total of 20 components were separated in only 8.0 min on a small particle size C18 column (1.7 microm). These components included nine diterpene acids, seven glycosides and four triterpenoids, among which pseudolaric acid C-O-beta-D-glucopyranoside and pseudolaric acid C2-O-beta-D-glucopyranoside were separated and identified for the first time in this study. Furthermore, the fragmentation patterns of the three types of compounds were elucidated for the first time. This established UPLC-PDA/Q-TOF-MS/MS method is reliable and effective for the separation and identification of the 20 compounds and will be useful for quality control of the crude Materials of Pseudolarix kaempferi Gordon and their related preparations.