Determination of quercetin and kaempferol in human urine after orally administrated tablet of ginkgo biloba extract by HPLC

A sensitive, simple and accurate method was developed for determination of quercetin and kaempferol in human urine by reversed phase high performance liquid chromatography. The urine samples were analyzed on C 18 column. Quercetin and kaempferol were analyzed simultaneously with good separation. UV detector was set at 380 nm. There was a linear relationship between chromatographic area of analytes and concentration of analytes over the concentration range 1.638–81.90 and 1.872–93.60 ng/ml for quercetin and kaempferol, respectively. The recovery of the assay was 99.7±6.2 and 97.4±7.2% for quercetin and kaempferol, respectively. The within-day and between-day coefficients of variation were less than 9.7 and 16.5% (RSD), respectively. The limit of detection was 1.0 ng/ml for quercetin and 1.1 ng/ml for kaempferol. The limit of quantitation was 1.61±0.11 ng/ml ( n=5) for quercetin and 1.85±0.11 ng/ml ( n=5) for kaempferol. The method developed has been applied to determine quercetin and kaempferol after orally administrated tablet of Ginkgo biloba extract in human urine.