Photometric Determination of Flavonoids in Parabarium Micranthum

The sample was extracted with methanol by refluxing at 80 ℃ in a Soxhlet′s extractor after removal of its impurities by refluxing with petroleum ether under the same condition.The extract was diluted to 100 mL in a volumetric flask with methanol,an aliquot of 1 mL was transferred to a 10 mL volumetric flask and the flavonoids were determined by its reaction with Al(Ⅲ) in an alkaline solution.Absorbance of the complex formed was measured at 510 nm.Rutin was used as standard in the preparation of calibration curve,the linearity of which was shown by the linear regression equation of C(mg·L-1)=0.096 69 A-0.000 763 (r=0.999 3).In applying the proposed method to analysis of Parabarium micranthum,93.0 mg·g-1 (n=6,RSD=1.62%) of flavonoids were found in the stems,and 96.4 mg·g-1 (n=6,RSD=0.44%) were found in the leaves.