A global profiling strategy using comprehensive two-dimensional liquid chromatography coupled with dual-mass spectrometry platforms: Chemical analysis of a multi-herb Chinese medicine formula as a case study

Although ultraviolet detector or mass spectrometer could be coupled with two-dimensional liquid chromatography (2DLC) to analyze complex constituents, full detection and identification of the compounds are difficult. Suffering from biased UV detection and insufficient MS data interpretation, a number of minor compounds are neglected though they are separated. In this study, we report a global chemical profiling strategy using comprehensive 2DLC coupled with dual-MS platforms, including Orbitrap-MS and QqQ-MS. It was exemplified by an 11-herb Chinese medicine formula Xiaoer-Feire-Kechuan (XFK). Firstly, constituents in XFK were separated on a CSH C18 × Phenyl-Hexyl 2DLC system with a practical peak capacity of 990.5 and an orthogonality of 90.3%. Secondly, untargeted mass spectral data was collected using dd-MS2 scan on an Orbitrap-MS. In total 542 peaks were detected, which was 4 times of that detected by 2DLC/UV (131 peaks). A total of 108 compounds were tentatively identified. Thirdly, targeted mass spectral data was collected for 8 characteristic substructures using neutral loss and precursor ion (NL/PRE) scan on a QqQ-MS. Extracted ion chromatogram was used to recognize minor constituents. An additional of 151 compounds were detected. Our study indicated that comprehensive 2DLC coupled with dd-MS2 and NL/PRE-MS is a powerful technique for the global profiling of multi-component systems.