Microwave-Assisted Extratrction of Flavonoids from Rhododendron dauricum L

A microwave-assisted extraction procedure was developed for flavonoids in Chinese herbal medicine Rhododendron dauricum L,using an open-vessel microwave-assisted extraction(MAE) device with temperature controlling.The influence of some operation conditions such as ethanol content,microwave irradiation time,temperature and liquid/solid ratio on the extraction yield of those compounds has been studied by using orthogonal test and optimization based on multivariate statistics.The experimental results show that the highest extraction yield can be obtained by using 80% ethanol as extraction solvent at 90℃,and microwave irradiation for 10 minutes with the ratio of liquid/solid of(40∶1.)Under the optimum conditions of MAE,there is a 16% increase of the extraction yield of flavonoids as compared with reflux extraction.