ELECTROSPRAY LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY OF GINSENOSIDES

An electrospray liquid chromatography/mass spectrometry (LC/MS) method has been developed for the analysis of ginseng saponins (ginsenosides) contained in extracts of the root of Panax ginseng (Korean ginseng) and Panax quinquefolius (American ginseng), The LC/MS method consists of separation of ginsenosides using an (aminopropyl)silica HPLC column, followed by detection using a photodiode array UV absorbance detector and then on-line electrospray mass spectrometry. Ginsenosides eluted from the HPLC column in order of increasing molecular weight and were detected as [M + Na](+) or [RI + 138](+) adducts, Occurrence of [M + 138](+) adducts was most prominent when new HPLC columns were used, and none were observed when solutions of ginsenoside standards were infused into the mass spectrometer without use of HPLC, The cation weighing 138 was identified as (3-ammoniumpropyl)trihydroxysilane, (NH4)-N-+(CH2)(3)Si(OH)(3), which was either a byproduct of stationary phase synthesis or a stationary phase degradation product. LC/MS chromatograms of extracts of Korean ginseng and American ginseng demonstrated substantial differences between the relative amounts of each ginsenoside, Based on molecular weight and coelution with standards, ginsenosides R(g1), R(e), R(d), R(c), R(b2), and R(b1) (in order of elution from the HPLC column) were identified in both ginseng extracts. Four other ginsenosides were detected by mass spectrometry for which no standards were available, and their molecular weights were 801 (possibly corresponding to ginsenoside R(f)), 817, 947, and 963 (possibly 20-gluco-R(f)), The ginsenosides weighing 817 and 963 were detected only in the Korean ginseng extract.