Abstract: Analysis of ginsenosides using high performance liquid chromatography-tandem atmospheric pressure chemical ionization mass spectrometry (HPLC-APCI/MS) has been carried out. HPLC analysis was performed on a reversed-phase C18 column using mobile phase of acetonitrile and water mixture under gradient elution. Effects of evaporation temperature of APCI-MS on identification of ginsenosides were investigated. APCI/MS-MS spectra of ［M-H］- were further resolved to identify the structures of ginsenosides. Detection limits of ginsenosides Rb1 and Rg1 were determined under selected reaction monitoring (SRM) mode. Ginsenosides in Panax ginseng (white ginseng) were assayed. Results show that although APCI is a high temperature evaporative process and ginsenosides are thermolabile compounds, abundant ［M-H］- ions could be detected by using APCI-MS. The intensity of ［M-H］- increased with the increase of evaporation temperature, which may due to more complete evaporation of elute solution at higher temperatures or due to the ionization mechanism of APCI. The detection limits of Rb1 and Rg1 were 1.2×10-13 g and 3.0×10-14 g, respectively. Twenty nine ginsenosides including malonyl-ginsenosides in Panax ginseng were identified. The method developed is sensitive, reproducible and accurate. Most ginsenosides in the extracts of ginseng could be effectively identified and analyzed for their structures.

Key words: atmospheric pressure chemical ionization mass spectrometry, ginsenosides, Panax ginseng (white ginseng) , high performance liquid chromatography