Sample Preparation of Standardized Extracts ofGinkgo biloba by Supercritical Fluid Extraction

Abstract

A method of sample preparation of standardized extracts of Ginkgo biloba using supercritical fluid extraction (SFE) is described. Ginkgolides and bilobalide could be selectively extracted with carbon dioxide containing 10% methanol at 335 atm and 45 °C from a methanolic solution of the extract. An in-line filter of silica gel was found to be essential for obtaining clean samples. Trapping was carried out with a solid silica gel trap at 80 °C. After eluting the trap with methyl acetate, the sample could be analysed by gas liquid chromatography or high performance liquid chromatography. Recoveries of the five terpenes relative to a standard solid phase extraction (SPE) procedure varied for two different extracts from 98.6 to 102.3%. Relative standard deviations were better for SFE than for SPE. A further advantage of the SFE over the SPE method is that it is much less laborious. A disadvantage is that it requires an automated supercritical extractor. With a small adaptation, the SFE method could also be used for finished ginkgo drugs in an aqueous alcoholic solution.