A multidimensional analytical approach based on time-decoupled online comprehensive two-dimensional liquid chromatography coupled with ion mobility quadrupole time-of-flight mass spectrometry for the analysis of ginsenosides from white and red ginsengs

Here, time-decoupled comprehensive two-dimensional ultra-high liquid chromatography (UHPLC) coupled with an ion mobility (IM)-high resolution mass spectrometer (HRMS) was established and used to analyze ginsenosides from the main roots of white ginseng (WG) and red ginseng (RG), which enabled the separation of complex samples in four dimensions (2D-LC, ion mobility, and mass spectrometry). The incompatibility of mobile phases, dilution effect, and long analysis time, which are the main shortcomings of traditional comprehensive 2D-LC methods, were largely avoided in this newly established 2D-UHPLC method. The orthogonality of this system was 55%, and the peak capacity was 4392. Under the optimized 2D-UHPLC-IM-MS method, 201 ginsenosides were detected from white and red ginseng samples. Among them, 10 pairs of co-eluting isobaric ginseng saponins that were not resolved by 2D-UHPLC-HRMS were further resolved using 2D-UHPLC-IM-MS. In addition, 24 ginsenoside references were analyzed by UHPLC-IM-MS to obtain their collision cross section (CCS) values and ion mobility characteristics. Finally, the established new method combined with multivariate statistical analysis was successfully applied to differentiate WG and RG, and 9 ginsenosides were found to be the potential biomarkers by S-Plot and the values of max fold change, which could be used for classifying WG and RG samples. Overall, the obtained results demonstrate the applicability and potential of the established time-decoupled online comprehensive 2D-UHPLC-IM-MS system, and it will be extended to the analysis of other targeted or untargeted compounds, especially co-eluting isomers in more herbal extracts.