Measurement of PCDDs,PCDFs,and non-ortho-PCBs by comprehensive two-dimensional gas chromatography-isotope dilution time-of-flight mass spectrometry (GCXGC-IDTOFMS)

摘要

Comprehensive two-dimensional gas chromatography with isotope-dilution time-of-flight mass spectrometry (GC x GC-IDTOFMS) was used to measure polychlorinated dihenzo-p-dioxin (PCDD).polychlorinated dibenzofuran (PCDF).and coplanar polychlorinated biphenyl (cPCB) concentrations in ash.sediment,vegetation,and fish samples.The GC x GC capability was achieved by using a quad jet.dual stage,thermal modulator.Zone compression of the GC peaks from modulation resulted in a significant increase of the signal intensity over classical GC-IDTOFMS.The GC" x GC column set used an Rtx-Dioxin 2 phase as the first dimension (~1D) and an Rtx-500 as the second dimension (~2D).The chromatographic separation of the 17 PCDD/Fs and the 4 cPCBs was attained in ~1D except for 2.3.7.8-TCDD and CB126 for which deconvolved ion currents (DIC) were required to be reported separately.The Rtx-500 phase separated the bulk matrix interfering compounds from the target analytes in :D.The instrumental limit of detection (iLODs) was 0.5 pg for 2.3.7.8-TCDD.The calibration curves showed good correlation coefficients for all the compounds investigated in the concentration range of 0.5-200 pg.GC x GC-IDTOFMS results compared favorably to those from conventional isotope-dilution one-dimensional gas chromatography-high resolution mass spectrometry (GC-IDHRMS).The comprehensive mass analysis of the TOFMS further permitted the identification of other contaminants of concern in the samples.