Rapid Identification of Different Types of Ginseng Samples by Internal Extractive Electrospray Ionization Mass Spectrometry

Ginseng is a precious traditional Chinese medicinal herb with over a thousand years of nutritional and medicinal application history. Known as the “King of Herbs”, its pharmacological effects exhibit significant variation, which stems from diverse planting and post-harvest conditions, including geographical origin, growing years, cultivation methods, and processing (e.g., fresh preservation and drying). The variety and commercial grade of ginseng are the core factors determining its quality and therapeutic efficacy. Therefore, the rapid and accurate identification of these attributes is crucial for ensuring the safety and efficacy of its clinical applications. To overcome the inherent limitations of traditional analytical methods, this study proposed a rapid identification method for ginseng based on internal extraction electrospray ionization mass spectrometry (iEESI-MS). This innovative technique enabled the direct acquisition of comprehensive chemical information from intact ginseng tissue without any sample pretreatment. The working principle is as follows: a charged extractant (methanol containing 0.5 mmol/L ammonium chloride) is infused into ginseng tissue to selectively extract bioactive compounds, which are then ionized and detected by the mass spectrometer. Using tandem mass spectrometry (MS/MS) analysis, combined with precise comparison against standards (including ginsenosides Rb₁, Re, and Rg₁) and cross-referencing with published literature, 25 chemical components were successfully identified in ginseng. To classify different ginseng samples, a classification model was constructed using orthogonal partial least squares discriminant analysis (OPLS-DA), a supervised multivariate statistical method. The OPLS-DA model effectively distinguished 13 types of ginseng samples, including 4 major varieties (garden ginseng, forest ginseng, Korean ginseng and red ginseng) and 3 commercial grades (small, medium and large) within each variety. This model has excellent predictive performance. In conclusion, this method has the advantages of no sample pretreatment, rapid analysis, and in-situ detection. By directly extracting chemical information from within plant tissues, this method not only facilitates direct comparison of different ginseng varieties and commercial grades, but also provides a material basis for elucidating the differences in their therapeutic efficacy.