Polychlorinated biphenyls chromatogram

An important application of carbon-skeleton gas chromatography is the simplification of the analysis of complex samples such as polychlorinated biphenyls, polybrominated biphenyls and polychloroalkanes [709-711], These complex mixtures of halogenated isomers produce multiple peaks when separated by gas chromatography, making quantitation difficult. The isomers have identical carbon skeletons, resulting in a very simple chromatogram after hydrodechlorination. 

Figure 13.2 MDGC-ECD chromatograms of PCB fractions from sediment samples, demonstrating the separation of the enantiomers of (a) PCB 95, (b) PCB 132, and (c) PCB 149 non-labelled peaks were not identified. Reprinted from Journal of Chromatography, A 723, A. Glausch et al., Enantioselective analysis of chiral polychlorinated biphenyls in sediment samples by multidimensional gas chromatography-electron-capture detection after steam distillation-solvent extraction and sulfur removal , pp. 399-404, copyright 1996, with permission from Elsevier Science.

Beezhold and Stout [68] studied the effect of using mixed standards on the determination of PCBs. Mixtures of Arochlors 1254 and 1260 were used as comparison standards and gas chromatograms of these mixtures were compared with those obtained from a hexane extract of the sample after clean-up on a Florasil column. Polychlorinated biphenyls were separated from DDT and its analogues on a silica gel column activated for 17h and with 2% (w/w) of water added. The extracts were analysed on a silanised glass column packed with 5% DC-200 and 7.5% QF-1 on Gas Chrom Q (80-100 mesh) operated at 195°C with nitrogen as carrier gas (50-60mL min-1) and a tritium detector. 

Figure 11, Total ion current chromatograms of (A) standard Aroclor 1260 mixture of polychlorinated biphenyls. Programmed temperature analysis two minutes at 206°C, to 230 C/min, isothermal at 230 C. (B) Human adipose tissue extract. Programmed temperature analysis two minutes at 190° C, to 230°C at 5°C/min, isothermal at 230°C.

The point that has been made so far from a theoretical standpoint has practical meaning in the laboratory. Figure 8 shows GLC chromatograms for standard solutions of p,p -DDE, a,p -DDT, and p,p -DDT, for a standard solution of polychlorinated biphenyls and of an extract of the liver of coho salmon, both concentrated and diluted (12). These were... 

Figure 11. Gas chromatograms (FID) of polychlorinated biphenyls from the environment and in an Arochr standard. (GC conditions are the same.)...

Figure 4. Gas chromatograms of the polychlorinated biphenyl. Aroclor 1254, recovered from silage and milk fat of cows fed the silage.

Figure 6.5 shows chromatograms of the same sample on a packed and capillary column. On top is a packed-column separation of AROCHLOR 1260 , a commercial blend of polychlorinated biphenyl compounds. A two-meter column of two-millimeter, i.d. glass was used with an electron capture detector. This chromatogram exhibits a plate number of about 1,500, and we observe about 16 peaks with this sample. 

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