title: The analysis of estrone and 17beta-estradiol by stir bar sorptive extraction-thermal desorption-gas chromatography/mass spectrometry: application to urine samples after oral administration of conjugated equine estrogens.
abstract: The development of a sensitive and solvent-free method for the measurement of estrone (E(1)) and 17beta-estradiol (17beta-E(2)) in human urine samples is described. The deconjugated estrogens were derivatized in situ with acetic acid anhydride and the derivatives were extracted directly from the aqueous samples using stir bar sorptive extraction (SBSE). The compounds containing a secondary alcohol function are further derivatized by headspace acylation prior to thermal desorption and gas chromatography/mass spectrometry (GC/MS). A number of experimental parameters, including salt addition, temperature and time, were optimized to increase the recovery of E(1) and 17beta-E(2) by SBSE. The derivatization reactions were also optimized to obtain the highest yields of the acylated estrogens. Detection limits of 0.02 and 0.03 ng mL(-1) were obtained for E(1) and 17beta-E(2), respectively. The method was applied to determine the effect of conjugated equine estrogen intake on the excretion of E(1) and 17beta-E(2) in human urine samples. Increased levels of the endogenous estrogens were detected after administering a standard dose of Premarin to a female volunteer. Routine monitoring of estrogen levels is recommended to avoid a high urinary excretion of E(1) and 17beta-E(2), nowadays enlisted as endocrine disrupting chemicals (EDCs), during hormone replacement therapy.
authors.affiliation: Department of Chemistry, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
authors.forename: Adriana
authors.initials: A
authors.lastname: Stopforth
authors.forename: Ben V
authors.initials: BV
authors.lastname: Burger
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Crouch
authors.forename: Pat
authors.initials: P
authors.lastname: Sandra
mesh_terms: D000284:Administration, Oral; D004958:Estradiol / Q000652:urine*; D004966:Estrogens, Conjugated (USP) / Q000008:administration & dosage*; D004970:Estrone / Q000652:urine*; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D004966:Estrogens, Conjugated (USP); D004970:Estrone; D004958:Estradiol