Determination of the content of the soybean isoflavone in functional food using high performance liquid chromatography method

The contents of 12 isoflavones in five kinds of commercial domestic and foreign soybean isoflavone functional food were determined with a high performance liquid chromatography method. For three isoflavone aglycones including daidzein, glycitein and genistein, three isoflavone glucosides including daidzin, glycitin and genistin were determined using their own standard materials and calibration curves with apigenin as internal standard. As to isoflavone malonyl glucosides, acetyl glucoside, their contents were calculated with the response factor of the respective glucoside forms and the conversion factors between them. The results indicated that the qualities of different brand soybean isoflavone functional food are quiet different. Some of them have the problem of false labeling. And even one product doesn't contain any isoflavone. Therefore, the inspection on the soybean isoflavone functional food market should be strengthened.