Determination of isoflavones in soy products by capillary electrophoresis with electrochemical detection

Simultaneous determination of daidzein and genistein in soy products by capillary electrophoresis with electrochemical detection (CE–ED) was reported. The effects of working electrode potential, running buffer pH, separation voltage and injection time on CE–ED were investigated. Under the optimum conditions, the analytes could be separated in a 100 mmol/l borate buffer (pH 11.0) within 20 min. A 300 μm diameter carbon disk electrode has a good response at +0.70 V (vs. SCE) for the analytes. The response was linear over three orders of magnitude for the analytes. This method has been satisfactorily used for the determination of daidzein and genistein in several actual soy samples.