High-pressure microwave extraction was used to extract the baicalin in Niuhuang Shangqing Pills.According to viscidity of honey pills,the sample was painted on the surface of unshaped glass slide,and then the glass slide was placed in extraction vessel and baicalin in the sample was extracted by microwave radiation.High performance liquid chromatograph(HPLC)was used to determine the content of baicalin.The effects of the microwave extraction pressure and time on the extraction yield of baicalin were also examined.The baicalin in Niuhuang Shangqing Pills obtained from five different factories was determined.The results indicate that the microwave extraction of method B(smearing)is obviously superior to the microwave extraction of method A(slicing),ultrasonic extraction and sexhlet extraction.This method proposed in the paper has advantages such as quickness,convenience and high extraction yield.
