HPLC with coulometric electrode array detection - Determination of daidzein and genistein in soy based infant food, soy milk and soy based supplements

A HPLC method coupled with coulometric electrode array detection for determ ination of daidzein and genistein in soy milk, soy-based infant food and nu tritional supplements is described. The samples were spiked with bisphenol A (internal standard), extracted and hydrolyzed in an acid ethanolic soluti on. After purification of the extract on a C-18 cartridge the compounds wer e separated on a C-18 reversed phase column (50 mM sodium acetate adapted t o pH 4.8 with glacial acetic acid/methanol at 450/550, v/v). The compounds were detected at eight electrodes set on potentials between +390 mV and +81 0 mV (in increments of 60 mV) against modified palladium electrodes. The co ntents of daidzein and genistein were determined in several commercial samp les.