On-line comprehensive two-dimensional liquid chromatography tandem mass spectrometry for the analysis of Curcuma kwangsiensis

A novel online comprehensive two-dimensional liquid chromatography (2DLC) coupled with quadrupole time of-flight (Q-TOF) mass spectrometry (MS) method is developed for the analysis of Curcuma kwangsiensis (C. kwangsiensis) extract. In this system, a newly developed phenyl/tetrazole sulfoether (PTAS) bonded stationary phase was introduced to construct RPLC x RPLC combined with C18. The unique structure endowed PTAS with very different selectivity from C18, reaching a high orthogonality of 93.2%. Moreover, such a combination settled compatibility issues because of the weaker hydrophobic retaining property of PTAS, thus allowing direct interfacing in online configuration. As a result of coupling with the mass spectrometry, a four-dimensional (4D) data plot was presented, in which 439 peaks (containing positive mode and negative mode) were counted, and 105 compounds were grouped and tentatively identified in C. kwangsiensis extract, including 73 unreported ones. Some novel types of compounds with masses exceeding 500 were discovered for the first time. Besides, compared to one-dimensional liquid chromatography (1DLC), the great resolution power of this system allowed separation of more isomers. These results provide supplementary to the material basis of C. Kwangsiensis and indepth research should be conducted. The configuration of RPLC x RPLC-Q-TOF MS can be a powerful and efficient tool for separation and characterization of chemical substances in complicated herbal extracts.