HPLC–MS/MS Analysis and Study on the Adsorption/Desorption Characteristics of Ginsenosides on Anion-Exchange Macroporous Resins

Abstract

Anion exchange resin is a modified version of polar/nonpolar macro porous resins with enhanced selectivity on compounds carrying negative charges. Although it is a promising adsorbent for the purification of natural products, no research regarding its application on ginsenosides has been reported elsewhere. In this paper, we first isolated total ginsenosides from Panax ginseng and investigated their static adsorption/desorption capacity on different resins, among which D301 resin was selected as the optimum one. A pH value of 8 was chosen for the balanced interaction between total ginsenosides and the adsorbents. Adsorption kinetics and isotherms of total ginsenosides on D301 and D101 resins were investigated to differentiate the adsorption characteristics of anion exchange and nonpolar macroporous resins. A D301-based chromatographic method was established to purify total ginsenosides with settings as follows: sample loading and elution speed = 4 bed volume per hour, breakthrough volume = 2 bed volume, elution solvent = 80% aqueous ethanol, elution volume = 8 bed volume. HPLC-QqQ-MS qualitatively and quantitatively analyzed nine individual ginsenosides from the eluates, demonstrating an enrichment factor of 5.3 as well as a recovery rate of 80.9% for the whole of these ginsenosides. The purity of these ginsenosides in Panax ginseng extract increased from 17.07% to 91.19% after the purification. Hence, anion exchange resin D301 proved to be a more comprehensive and efficient adsorbent than the conventional nonpolar macroporous resin for the separation of total ginsenosides from natural sources. Based on the findings in this paper, the enrichment process for total ginsenosides could be well established via one-step column chromatography.