FormNo. 203-821-250 01/05-REV0
LECO is a registered trademark of LECO Corporation
1
Separation Science Application Note
GCxGC
Quantificationof Dioxin-LikePolychlorinated
BiphenylsUsingGCxGC-ECDwith aSelective
Column in theSecondDimension
Introduction
Certain polychlorinated biphenyls (PCBs), thosewith no or only one ortho-chlorine substitution,
exhibit dioxin-like toxicity due to their ability to take planar shapes in space. When determining
PCBs in a variety of environmental samples, many analytical schemes focus on those congeners,
and it is important that any quantitative values are free from bias. This is sometimes a challenge
due to the fact that there are 209 possible PCB congeners, and also because dioxin-like PCBs are
almost always at much lower concentrations in samples than other PCBs. For these reasons, the
chromatographic separation of PCBsmust be highly efficient.
Comprehensive two-dimensional GC (GCxGC) is oneway to determine dioxin-like PCBs with a
higher degree of selectivity. GCxGC increases peak capacity by applying two independent
separations to a sample in one analysis with one detector. This application notewill demonstrate
the possibility of usingGCxGC-ECD to quantify dioxin-like PCBs in environmental samples with an
example of their quantification in an Aroclor 1254 dilution.
Standards
PCB standardmixes that included the dioxin-like PCBs shown in Table 1 and Aroclor 1254were
obtained from AccuStandard (NewHaven, Connecticut, USA). An organochlorine pesticide standard
mix was obtained from Restek Corporation (Bellefonte, Pennsylvania, USA).
Experimental Conditions
LECOGCxGC-ECD
Agilent 6890 GC-ECD equippedwith a LECOQuad Jet—Dual-Stage Thermal Modulator
Column 1:
50m x 0.18mm x 0.18 µm Rtx-1 (Restek)
Column 2:
1.5m x 0.18mm x 0.10 µm Rtx-PCB (Restek)
Carrier:
Helium at 1.3mL/min, constant flow
Injection:
1 µL split at 250°C, split ratio 20:1
Oven 1 Program: 160°C (0.2min), 2°/min to 280°
Oven 2 Program: 20°C offset from oven 1
Modulation Time: 8 sec.
Detector:
ECD, 325°C, N
2
makeup gas at 148.7mL/min, 50 Hz
