title: Comprehensive two-dimensional gas chromatography with isotope dilution time-of-flight mass spectrometry for the measurement of dioxins and polychlorinated biphenyls in foodstuffs. Comparison with other methods.
abstract: A comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC x GC-TOF-MS) experimental setup was tested for the measurement of seven 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs), ten 2,3,7,8-substituted polychlorinated dibenzofurans (PCDFs), four non-ortho-polychlorinated biphenyls (PCBs), eight mono-ortho-PCBs, and six indicator PCBs (Aroclor 1260) in foodstuff samples. A 40m RTX-500 (0.18mm I.D., 0.10 microm df) was used as the first dimension (1D) and a 1.5 m BPX-50 (0.10mm I.D., 0.10 microm df) as the second dimension (2D). The GC x GC chromatographic separation was completed in 45 min. Quantification was performed using 13C-label isotope dilution (ID). Isotope ratios of the selected quantification ions were checked against theoretical values prior to peak assignment and quantification. The dynamic working range spanned three orders of magnitude. The lowest detectable amount of 2,3,7,8-TCDD was 0.2 pg. Fish, pork, and milk samples were considered. On a congener basis, the GC x GC-ID-TOF-MS method was compared to the reference GC-ID high resolution mass spectrometry (HRMS) method and to the alternative GC-ID tandem-in-time quadrupole ion storage mass spectrometry (QIST-MS/MS). PCB levels ranged from low picogram (pg) to low nanogram (ng) per gram of sample and data compared very well between the different methods. For all matrices, PCDD/Fs were at a low pg level (0.05-3 pg) on a fresh weight basis. Although congener profiles were accurately described, RSDs of GC x GC-ID-TOF-MS and GC-QIST-MS/MS were much higher than for GC-ID-HRMS, especially for low level pork and milk. On a toxic equivalent (TEQ) basis, all methods, including the dioxin-responsive chemically activated luciferase gene expression (DR-CALUX) assay, produced similar responses. A cost comparison is also presented.
authors.affiliation: CART Mass Spectrometry Laboratory, Chemistry Department, University of Liège, Allée de la Chimie 3, B-6c Sart-Tilman, B-4000 Liège, Belgium. JF.Focant@ulg.ac.be
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Focant
authors.forename: Gauthier
authors.initials: G
authors.lastname: Eppe
authors.forename: Marie-Louise
authors.initials: ML
authors.lastname: Scippo
authors.forename: Anne-Cécile
authors.initials: AC
authors.lastname: Massart
authors.forename: Catherine
authors.initials: C
authors.lastname: Pirard
authors.forename: Guy
authors.initials: G
authors.lastname: Maghuin-Rogister
authors.forename: Edwin
authors.initials: E
authors.lastname: De Pauw
mesh_terms: D004147:Dioxins / Q000032:analysis*; D005504:Food Analysis; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D011078:Polychlorinated Biphenyls / Q000032:analysis*
chemical_list: D004147:Dioxins; D011078:Polychlorinated Biphenyls