title: Column-switching high-performance liquid chromatography electrospray mass spectrometry coupled with on-line of extraction for the determination of mono- and di-(2-ethylhexyl) phthalate in blood samples.
abstract: A novel method based on column-switching high-performance liquid chromatography-electrospray mass spectrometry (LC-MS) coupled with an on-line extraction column containing conjugated avidin has been developed for direct injection analysis of di(2-ethylhexyl) phthalate (DEHP) and its metabolite, mono(2-ethylhexyl) phthalate (MEHP), in blood samples. The sample preparation for on-line extraction involved the mixing of blood samples with internal standards, DEHP-d(4) and MEHP-d(4), in LC glass vials. A linear response was found for column-switching LC-MS when tests were conducted within the validated range of 25 to 1000 ng mL(-1) for DEHP and 5 to 1000 ng mL(-1) for MEHP, with correlation coefficients (r) greater than 0.999. In addition, the recoveries of DEHP and MEHP from human plasma were calculated by using this method with on-line extraction, yielding recoveries of up to 91.2% (RSD<5%). We measured the background levels of DEHP and MEHP in six human plasma samples from healthy volunteers and three fetal bovine serum samples for cell-line culture. DEHP and MEHP were not detected in all human plasma samples (N.D. is <25 ng mL(-1) for DEHP, and N.D. is <5.0 ng mL(-1) for MEHP). In contrast, high DEHP contamination of commercially available fetal bovine serum samples was found by this method.
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Inoue
authors.forename: Migaku
authors.initials: M
authors.lastname: Kawaguchi
authors.forename: Fumio
authors.initials: F
authors.lastname: Okada
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yoshimura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakazawa
mesh_terms: D000328:Adult; D000818:Animals; D001331:Automation; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation; D004051:Diethylhexyl Phthalate / Q000031:analogs & derivatives* / Q000097:blood*; D004864:Equipment and Supplies / Q000009:adverse effects; D005333:Fetus; D006801:Humans; D010968:Plasticizers / Q000032:analysis; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation*
chemical_list: D010968:Plasticizers; D004051:Diethylhexyl Phthalate; C016599:mono-(2-ethylhexyl)phthalate