Abstract: This paper deals with the ethanolalkali extraction method of astragalus polysaccharides, by which the effects of five extraction factors including pH of extraction solvent, the ratio of material to extraction solvent,extraction time, extraction temperature and ethanol concentration of extraction solvent on the rate of extraction were studied. The extraction rate of astragalus poly saccharides extracted by ethanolalkali extraction method was compared with those of water extraction method and alkaliextraction method and the content of astragaluspolysaccharides extracted by ethanolalkali extraction method was detected by ultraviolet spectrophotometry and infrared spectrometry. The results show that the extraction rate of ethanolalkali extraction method is 19.15%, 3.53 times that of water extraction method and 2.63 times that of alkali extraction method, the residue of the efficiency components of ethanolalkali extraction method is less than those of the other methods.

Key words: astragalus polysaccharides, ethanolalkali extraction method, infrared spectrometry