Determination of quercetin and kaempferol in Ginkgo biloba extract by supercritical fluid extraction and micellar electrokinetic capillary chromato-graphy

Objective: To establish a method for the determination of quercetin and kaempferol in Ginkgo biloba extract. Methods: A simple, rapid and reproducible supercritical fluid extract (SFE) and capillary electrophoretic method were developed for it. SFE was selected by orthogonal design method. SFE conditions: temperature 60 ℃, pressure 42 mPa, static extraction 4 min, dynamic extraction volume 4 ml and 0.2 ml ethanol as modifier. MECC conditions were 55 cm×75 μm fused silica capillary column. The running buffer contained 25 mmol/L sodium dihydrophosphate, 6.25 mmol/L sodium borate (pH= 8.5) and 35 mmol/L sodium dodecyl sulfate(SDS). The detection wave length was at 254 nm. Results: The influence of modifier on extraction rate in SFE was the most. The linear range for quercetin and kaempferol was 21.2 106.0, 20.0 100.0 μg/ml, respectively, when cinnamic acid was in an internal standard. The recovery of quercetin for 40, 60 and 80 μl was 93.87%, 94.02% and 94.10%, respectively. The recovery of kaempferol for 40, 60 and 80 μl was 94.50%, 94.17% and 94.25%, respectively. Conclusion: SFE MECC is convenient and accurate method, and can be used as a measure of quality control for Ginkgo biloba extract. [