A Comparative Study on Two Microwave-Assisted Extractions of Ingredient Flavonoids from Rhododendron dauricum L.

Two microwave-assisted extraction procedures,open-vessel device and closed-vessel device,were developed and compared for flavonoids in Chinese herbal madicine Rhododendron dauricum L..The effect of the solvent consistence is 115.6% when microwave radiation time is 10 min,temperatures is 90 ℃ and liquid/solid ratio is 40∶1.The effect of the solvent consistence is 114.0% when microwave radiation time is 20 min,pressure is 600 kPa,and liquid/solid ratio is 20∶1.Compared with traditional refluence extraction,microwave-assisted extraction is even more efficient,and the open-vessel microwave-assisted device is more efficient than the closed-vessel device.