Spectrophotometric Determination of Total Flavonoids in Dandelion with Bi-aqueous Phase Ultrasonic Extraction

Total flavonoids in 50 mg of dandelion powder was ultrasonically extracted for 30 min from the medium containing 2.0 mL of n-propyl alcohol and 2.5 g of NaH2PO4. The flavonoids in the n-propyl alcohol phase, was separated and evaporated to dryness. The residue obtained was dissolved and made up to 50 mL with C2H5OH-H2O (1+1) solution, and its absorbance measured at 510 nm. Linear relationship between values of absorbance and mass concentration of total flavonoids was kept in the range of within 8.0 mg·L-1. The proposed method was applied to the determination of total flavonoids in dandelion, with value of extraction rate achieved to 4.12%.