title: Stir-bar-sorptive extraction, with in-situ deconjugation, and thermal desorption with in-tube silylation, followed by gas chromatography-mass spectrometry for measurement of urinary 4-nonylphenol and 4-tert-octylphenol glucuronides.
abstract: A novel method, stir-bar-sorptive extraction (SBSE), with in-situ deconjugation and thermal desorption (TD) with in-tube silylation, followed by gas chromatography-mass spectrometry (GC-MS), for determination of trace amounts of 4-nonylphenol glucuronide (NP-G) and 4-tert-octylphenol glucuronide (OP-G) in human urine, is described. The method involved correction by use of stable isotopically labeled internal standards 4-(1-methyl)octylphenol-d5 (NP-d) and deuterium 4-tert-octylphenol (OP-d). A human urine sample to which beta-glucuronidase had been added was extracted for 90 min at 37 degrees C using a stir bar coated with a 500-microm-thick layer of polydimethylsiloxane (PDMS). NP-G and OP-G were deconjugated, becoming free 4-nonylphenol (NP) and 4-tert-octylphenol (OP). The analytes were then extracted with the PDMS stir bar and the stir bar was subjected to TD with in-tube silylation; this was followed by GC-MS in selected-ion-monitoring (SIM) mode. To optimize the conditions for SBSE with in-situ deconjugation and to test recovery, NP-G and OP-G were synthesized by a biochemical technique in our laboratory. Average recoveries from human urine samples spiked with NP-G and OP-G were between 91.9 and 95.6% with correction using the added surrogate standards. Limits of detection were 0.11 ng mL-1 for NP and 0.01 ng mL-1 for OP. We also measured background levels of NP-G and OP-G in six urine samples from healthy volunteers. NP and OP were detected in the samples at concentrations of 0.62-1.95 ng mL-1 and <0.04-0.18 ng mL-1, respectively.
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan.
authors.forename: Migaku
authors.initials: M
authors.lastname: Kawaguchi
authors.forename: Rie
authors.initials: R
authors.lastname: Ito
authors.forename: Norihiro
authors.initials: N
authors.lastname: Sakui
authors.forename: Noriya
authors.initials: N
authors.lastname: Okanouchi
authors.forename: Koichi
authors.initials: K
authors.lastname: Saito
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Seto
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakazawa
mesh_terms: D000328:Adult; D000465:Algorithms; D004781:Environmental Exposure / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D005966:Glucuronidase / Q000737:chemistry; D020719:Glucuronides / Q000138:chemical synthesis / Q000737:chemistry / Q000652:urine*; D006801:Humans; D007096:Imidoesters / Q000737:chemistry; D015394:Molecular Structure; D010636:Phenols / Q000652:urine*; D015203:Reproducibility of Results; D013696:Temperature; D014297:Trimethylsilyl Compounds / Q000737:chemistry
chemical_list: D020719:Glucuronides; D007096:Imidoesters; D010636:Phenols; D014297:Trimethylsilyl Compounds; C080718:N,O-bis(trimethylsilyl)acetamide; D005966:Glucuronidase; C041594:4-nonylphenol; C105260:4-tert-octylphenol