HPLC-LTQ-orbitrap MSn profiling method to comprehensively characterize multiple chemical constituents in xiao-er-qing-jie granules
In the present study, a method based on high performance liquid chromatography coupled with linear ion trap-orbitrap mass spectrometry (HPLC-LTQ-orbitrap) was developed for a comprehensive study of the multiple chemical constituents in xiao-er-qing-jie (XEQJ) granules, which are regularly used as a traditional Chinese medicine (TCM) for the treatment of children with high fever, sore throat, and lusterless complexion. Seven major categories of constituents preliminarily isolated from the component herbs were rapidly characterized using HPLC-LTQ-orbitrap. The fragmentation patterns of these compounds with different skeletons were clearly elaborated in the electrospray ionization (ESI) collision induced dissociation (CID)-MS/MS experiments. Based on the accurate mass measurement (<5 ppm), MS/MS fragmentation patterns, diagnostic product ions, and different chromatographic behaviors, 91 compounds were unambiguously identified or tentatively characterized, including 33 phenylethanoid glycosides, 13 phenolic acids, 11 flavonoids, 10 alkaloids, 9 lignans, 9 iridoid glycosides, and 6 saponins. Among them, 2 compounds were potential new ones from Forsythiae Fructus and 24 were unambiguously confirmed by comparing with their respective reference standards. The results demonstrated that our established method was useful and efficient to screen and identify targeted constituents from TCM extracts and other organic matter mixtures whose constituent compounds can also be classified into families on the basis of common carbon skeletons.