Detection of the isoflavone aglycones genistein and daidzein in urine using solid-phase microextraction-high-performance liquid chromatography-electrospray ionization mass spectrometry

An improved method of detection of the isoflavone aglycones, genistein and daidzein, is reported using solid-phase microextraction-high-performance liquid chromatography-electrospray ionization mass spectrometry (SPME-HPLC-ESIMS). Extraction of the isoflavonoids from urine using SPME with a Carbowax-templated resin fiber coating allows rapid preconcentration of the analytes without the usual sample preparation required by other methods. Detection of the analytes is accomplished by HPLC-ESI-MS. Analysis of spiked samples of urine resulted in a linear range of 0.25 to 250 ng/ml for daidzein and 0.27 to 27.0 ng/ml for genistein. Limits of detection of daidzein and genistein were measured at 25.4 pg/ml for daidzein and 2.70 pg/ml for genistein. Daidzein and genistein were detected in urine following consumption of a soy drink. (C) 2001 Elsevier Science B.V. All rights reserved.