Rapid Differentiation of Asian and American Ginseng by Differential Ion Mobility Spectrometry-Tandem Mass Spectrometry Using Stepwise Modulation of Gas Modifier Concentration.

This study reports a rapid and robust method for the differentiation of Asian and American ginseng samples based on differential ion mobility spectrometry-tandem mass spectrometry (DMS-MS/MS). Groups of bioactive ginsenoside/pseudo-ginsenoside isomers, including Rf/Rg/F, Rb/Rb/Rc, and Rd/Re, in the ginseng extracts were sequentially separated using DMS with stepwise changes in the gas modifier concentration prior to MS analysis. The identities of the spatially separated ginsenoside/pseudo-ginsenoside isomers were confirmed by their characteristic compensation voltages at specific modifier loading and MS/MS product ions. As expected, Asian ginseng samples contained some Rf and an insignificant amount of F, whereas American ginseng samples had a high level of F but no Rf. The origin of the whole and sliced ginseng could further be confirmed using the quantitative ratios of three sets of ginsenoside markers, namely, Rg/Re, Rb/Rg, and Rb/Rc. Based on our results, new benchmark ratios of Rg/Re < 0.15, Rb/Rg > 2.15, and Rb/Rc < 0.26 were proposed for American ginseng (as opposed to Asian ginseng).