ABSTRACT
<p><b>AIM</b>To identify the hydroxylate metabolites and its sulfate conjugates of daidzein in rat urine.</p><p><b>METHODS</b>Urine samples from 0 - 24 h were collected after single ig dose of 500 mg x kg(-1) daidzein to each of six rats. The urine samples were purified by SPE column (SPE C18) and analyzed with liquid chromatographic-tandem electrospray ionization ion trap mass spectrometry (LC-ESI/MS(n)) for potential metabolites.</p><p><b>RESULTS</b>Several new hydroxylate metabolites and its sulfate conjugates were found and identified in rat urine.</p><p><b>CONCLUSION</b>LC-ESI/MS(n) is proved to be a simple, rapid, sensitive and specific technique for identification of the hydroxylate metabolites and its sulfate conjugates of daidzein in rat urine.</p>