HPLC, HPLC-electrospray ionization (LC-ESI), and LC-FABMS were used to characterize flavonoid glycosides in the methanol extract from peanut meal. Five isoflavones, daidzin, glycitin, genistin, daidzein, and genistein, were separated by HPLC and characterized by comparison with known standards using ESI-MS. The flavonoid methylquercetin (rhamnetin) was present in the methanol extract from peanuts and identified by ESI-MS. Four other flavonoids, two quercetin diglycosides, one quercetin monoglucoside, and isorhamnetin glucoside, were found to be present in the methanol extract based on their reversed-phase elution pattern, mass ions, and fragment ions using flow-FABMS. FIG. 2. HPLC chromatogram overlay of the MeOH extract from peanut meal and a standard mixture of the isoflavones daidzin (1), glycitin (2), genistin (3), daidzein (4), and genistein (5).FIG. 1. Isoflavone skeleton, positional specificity, and M.W.