A novel and effective mode-switching triple quadrupole mass spectrometric approach for simultaneous quantification of fifteen ginsenosides in Panax ginseng

Background: Panax ginseng (PG) is one of the most valuable and frequently used phytomedicine in Asia. In the current Chinese Pharmacopeia, only three ginsenosides, Rg1, Re and Rb1, were set as standard compounds for the quality evaluation of PG. However, only these three compounds could hardly reflect the quality and therapeutic efficacy of this traditional Chinese medicine (TCM).

Purpose: Quantification analysis of quality markers (Q-markers) in PG is meaningful for determining the quality of this herbal medicine.

Method: By combining the modes of multiple reaction monitoring (MRM) and single ion monitoring (SIM) of tripe quadrupole mass spectrometry (QqQ-MS) through a mode-switching function, a novel, sensitive and effective LC-MS/MS method has been established to simultaneous quantify fifteen Q-markers in PG in one run time cycle. In order to comprehensively evaluate the quality of ten batches of PG, hierarchical clustering analysis (HCA) and the complete linkage method were conducted on the data of the contents of fifteen ginsenosides.

Results: Thirteen Q-markers, including four pairs of isomers with the same product ions and approximately the same retention times, have been well-separated by MRM. Meanwhile, the other two Q-markers with no fragments have also been quantified by SIM. Chromatographic separation was carried out on a reversed-phase C₁₈ column by stepwise gradient elution with a mobile phase of water (containing 0.1% formic acid, v/v) and acetonitrile. Good linearity was observed with the correlation coefficients (r²) greater than 0.99. The intra- and inter-day precisions as well as repeatability of all of the investigated Q-markers were all no more than 5.91%. The average recoveries varied from 83.06% to 116.42%, with relative standard deviation values (RSDs) less than 6.73%. The total contents of the fifteen ginsenosides in ten batches of PG were in the range of 15.54-24.03 mg/g. The results indicated that the growing region has a significant impact on the contents of ginsenosides in PG.

Conclusion: The proposed approach could be readily utilized as a comprehensive approach for determining the consistency of the quality and therapeutic efficacy of PG, and it might be an example for the selection of Q-marker standards for the Chinese Pharmacopoeia.