Rybak, Michael E., et al. Journal of Chromatography B, 2008, 861(1), 145-150.
Researchers examined how atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) performed in quantifying six urinary phytoestrogens including daidzein, O-desmethylangolensin, equol, enterodiol, enterolactone, and genistein using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The quantitative analysis required the use of deuterated internal standards including 2H3-daidzein, 2H4-equol, 2H5-O-desmethylangolensin, 2H8-enterodiol, 2H6-enterolactone, and 2H4-genistein.
Key Findings
Both ESI and APCI techniques are suitable for the quantitative determination of selected urinary phytoestrogens by LC-MS/MS. ESI showed better method precision than APCI while producing strong agreement between both methods in random patient urine sample analysis when sensitivity limitations were not significant. The ESI technique achieved comparable or superior analyte sensitivity to APCI while significantly enhancing detection rates for equol which has been traditionally difficult to quantify. ESI should be chosen for biomonitoring urinary daidzein, O-desmethylangolensin, equol, enterodiol, enterolactone, and genistein when studies need high sensitivity and reproducibility because it offers these benefits without significant ionization source discrepancies.
