title: Automated online and off-line solid-phase extraction methods for measuring isoflavones and lignans in urine.
abstract: Automated online and off-line solid-phase extraction (SPE) methods coupled to isotope dilution-high-performance liquid chromatography-tandem mass spectrometry for measuring four isoflavones (daidzein, genistein, equol, and O-desmethylangolensin) and two lignans (enterolactone and enterodiol) in urine are developed. The SPE recoveries for the online SPE method are excellent for most analytes (83-94%) and somewhat lower for enterolactone (61%). The recoveries for all analytes with the off-line SPE method are also very good (65-80%). The limit of detection is lower for the online method (0.1-0.7 ng/mL) than for the off-line method (0.4-3.3 ng/mL). Similarly, the reproducibility is generally better for the online method [coefficient of variation (CV) of 4-12%) than for the off-line method, except for enterolactone, which has a higher CV (18-19%) that is consistent with its lower online SPE recovery. Both methods are adequate for analyzing a large number of samples for epidemiological studies to assess the prevalence of human exposure to isoflavones and lignans.
authors.affiliation: Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA.
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Kuklenyik
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Ye
authors.forename: John Adam
authors.initials: JA
authors.lastname: Reich
authors.forename: Larry L
authors.initials: LL
authors.lastname: Needham
authors.forename: Antonia M
authors.initials: AM
authors.lastname: Calafat
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D007529:Isoflavones / Q000652:urine*; D017705:Lignans / Q000652:urine*; D013058:Mass Spectrometry / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D007529:Isoflavones; D017705:Lignans