A chemical profiling solution for Chinese medicine formulas using comprehensive and loop-based multiple heart-cutting two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

ABSTRACT

Chinese medicine formulas represent an excellent illustration for "complex matrix". The complexity lies in a big array of small molecules with high chemical diversity. The present paper describes a novel chemical profiling solution for complex matrix by combining comprehensive and multiple heart-cutting two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (2DLC/qTOF-MS). This solution includes method optimization, combinational separation, and structural characterization. It was exemplified by fully profiling the chemical constituents of a four-herb traditional Chinese medicine formula, Gegen-Qinlian Decoction (GQD). GQD was separated by a RP × RP (C18 × Phenyl-Hexyl) 2DLC system, and eluted with acidic × alkaline mobile phases with an optimized shift gradient elution program. In the comprehensive 2DLC mode, 280 peaks were detected, and 125 compounds were characterized within 42 minutes. The multiple heart-cutting (MHC) mode extended the (2)D modulation time to 3.0 min to effectively separate the minor compounds. The (1)D eluate within 4.4 min was loaded into eleven 40-µL loops. These fractions were successively separated by (2)D to resolve 13 additional compounds. The combination of comprehensive and MHC 2DLC/qTOF-MS provides a powerful technique for global chemical profiling of Chinese medicine formulas and other complex systems.