Comprehensive online two-dimensional liquid chromatography coupled to hybrid linear ion trap Orbitrap mass spectrometry with optimized dilution and modulation for analysis of Huangqi Guizhi Wuwu decoction

Huangqi Guizhi Wuwu decoction (HGWD), as a classical formula, has been used for thousands of years in China. In this work, a comprehensive strategy was proposed for characterizing the chemical profile of HGWD based on online two-dimensional hydrophilic interaction and reversed-phase liquid chromatography coupled with hybrid linear ion trap-Orbitrap mass spectrometry (online HILIC × RP-ESI/HRMS/MS n ). The compounds in HGWD were first separated by the combined use of an XBridge amide column (150 × 4.6 mm, 3.5 μm) and Accucore C18 column (50 mm × 4.6 mm, 2.6 μm). Modulation with assistant technology, including trap columns and online dilution, was optimized and developed to decrease potential analyte loss and improve the resolution of the system. Subsequently, the accurate mass was determined by high-resolution Orbitrap and MS n fragment data by a hybrid linear ion trap (LTQ). In total, 170 chemical constituents were unambiguously identified or tentatively characterized in both positive and negative ion modes. Our study demonstrated that the proposed online HILIC × RP system coupled to the LTQ-Orbitrap MS platform is an efficient analytical technique for characterizing the chemical profile of multicomponent systems.