The root of North American ginseng (Panax quinquefolius) was extracted using conventional solvent techniques (Soxhlet) and using supercritical fluid extraction (SFE). SFE was accomplished using modified supercritical carbon dioxide (scCO(2)), with methanol and DMSO as modifiers. At a temperature of 110 degrees C and a modifier to solid ratio of 4.1 g of modifier per gram of ginseng, the system pressure was found to have no significant effect on the quantity of ginsenosides extracted from 20.7 to 48.3 MPa using CO2 +methanol. In addition, the process was shown to be mass transfer/desorption limited rather than solubility limited under these conditions. For the studied SFE conditions, up to 90% of the total ginsenosides were extracted compared to conventional methanol Soxhlet, as determined by HPLC analysis. A relatively unknown ginsenoside peak was observed in the HPLC chromatograms for all supercritical extractions, particularly those employing DMSO as a modifier. This peak was identified as 6"/6"" -mono-O-acetyl ginsenoside Rb-1 by LC/MS. (C) 2006 Elsevier B.V. All rights reserved.