Evaluation of quantitative analysis of flavonoid aglycones in Ginkgo biloba extract and its products

A simple and rapid HPLC method was developed to evaluate and validate the assay of quercetin, kaempferol and isorhamnetin in Ginkgo biloba extract and its products. The column used is Cosmosil 5C18-AR, and mobile phase is MeOH:0.3%H3PO4 (1:1). The correlation coefficients of linear calibration for quercetin, kaempferol and isorhamnetin are 0.9999, 0.9999, and 0.9989, respectively. The relative standard deviations of intra-day assays for quercetin, kaempferol, and isorhamnetin are 0.29%, 0.28%, and 1.90%, respectively; interday assays are 0.95%, 0.85%, and 1.67%, respectively. The recoveries of quercetin, kaempferol and, isorhamnetin are 87.4%, 94.0%, and 72.4%, respectively. The optimal condition for acid hydrolysis of flavonoid glycosides in Ginkgo biloba extract could be achieved by refluxing with 20.0% HCl at 85°C for 15 min or with 5.5% HCl at the same temperature for 30 min.