Sensitive high-performance liquid chromatographic method for profiling phytoestrogens using coulometric electrode array detection: Application to plasma analysis

An HPLC method for profiling 13 phytoestrogens and their metabolites using coulometric electrode array detection was developed, Sensitivity of the met hod was slightly less than that of-our GC-MS method, but significantly high er compared to the HPLC methods using diode-array or UV detection. Detectio n limits varied from 3.4 (secoisolariciresinol) to 40.3 (genistin) pg on co lumn. Signal linearities ranged from the detection limits to 61 ng on colum n. Resolution values for the peak pairs varied from 1.1 (O-desmethylangolen sin-anhydrosecoisolariciresinol) to 16 (daidzin-genistin). Intra- and inter assay retention time variations were negligible and detector response varia tion was eliminated by frequent calibration. Chromatographic method was app lied to plasma analyses and 6 of the 13 compounds were detected. Method acc uracy for those six analytes varied from 69% (enterodiol) to 118% (genistei n), Intraassay precision CVs ranged from 1.5% (enterolactone, 12.4 nmol/lit er) to 14% (genistein, 245 nmol/liter) and interassay precision CVs ranged from 9.9% (daidzein, 67.4 nmol/liter) to 44% (enterodiol, 1.20 nmol/liter). (C) 1999 Academic Press.