ANALYSIS OF ISOFLAVONES IN NATURAL SOURCES AND NUTRITIONAL SUPPLEMENTS BY LIQUID CHROMATOGRAPHY AND MULTI-CHANNEL ELECTROCHEMICAL DETECTION

Abstract

A simple gradient reverse-phase liquid chromatographic method has been developed for the separation of daidzin, genistin, daidzein, and genistein in various natural sources and dietary supplements. Peak assignment at various retention times was confirmed by comparison of the simultaneous response of sample peaks to standards, at glassy carbon electrodes held at different oxidation potentials, using a multi-channel electrochemical detector. Identification was substantiated by ESI MS/MS fragmentation patterns. The analytes of interest were extracted by sonicating raw materials in cold 80% methanol/water for 10 minutes. The concentration of the named isoflavones in various dry food and nutritional supplements was determined using the present LCEC procedure.