- Mechanism of PCBs formation from the pyrolysis of chlorobenzenes
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Polychlorinated biphenyls (PCBs) were formed by pyrolysis of chlorobenzenes in a HCl atmosphere. Varieties of substituted chlorobenzenes were used as model compounds to optimize the condensation reaction. Lower chlorinated benzenes produce more PCBs than that of higher ones. Up to 0.7 μg PCBs/mg 1,2,3-trichlorobenzene was produced through the condensation reaction.
- Liu, Peng-Yan,Zheng, Ming-Hui,Zhang, Bing,Xu, Xiao-Bai
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p. 783 - 785
(2007/10/03)
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- Physical, spectral and chromatographic properties of all 209 individual PCB congeners
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Through the use of two capillary GC columns: 40% octadecyl/ 15% phenyl methyl siloxane and 50% phenyl methyl siloxane, it was possible to separate 201 PCB congeners with only four unresolved pairs. The data compiled in this study for all 209 congeners will aid in the identification of selected individual components of these environmental pollutants. The use of this data also presents the opportunity for the improved quantification of the commercial PCB formulations. -from Authors
- Bolgar,et al.
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p. 2687 - 2705
(2007/10/03)
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- SYNTHESIS AND MASS SPECTROMETRY OF SOME METHOXYLATED PCB
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The syntheses of 46 methoxy-polychlorobiphenyls (MeO-CBs), containing 3 to 7 chlorine atoms, are described. The MeO-CBs were synthesized via the Cadogan diaryl coupling reaction of the appropriate polychloroaniline and polychloroanisole, or via the Ullmann coupling of a polychloroiodobenzene and 4-iodoanisole with subsequent chlorination of the isolated 4-MeO-CB product. The synthesized MeO-CBs were characterized by electron ionization (EI) mass spectrometry (MS) on an ion trap MS instrument and by EI and negative ion chemical ionization (NICI) on a quadrupole mass spectrometer. Both instruments gave similar EI spectra but the fragments were in general more abundant relative to the molecular ion, in the spectra obtained from the ion trap instrument. Characteristic fragmentation patterns were obtained by EI for ortho-, meta- and para-MeO-CBs, respectively, depending on the position of the MeO-group, with the exception of three meta-substituted MeO-heptaCBs, with a 3-MeO-2,4,6-trichloro-substitution pattern, that gave an abundant +-fragment, similar to para-substituted MeO-CBs. MS(NICI) of ortho-, meta- and para-MeO-CBs did not give any characteristic fragmentation patterns depending on the position of the MeO-group, except for ortho-substituted MeO-CBs that showed abundant fragments at -. The MS(NICI) gave approximately 10-50 times higher response for MeO-tetraCBs - MeO-heptaCBs than the MS(EI). The ion trap instrument (ITS40) has a somewhat lower detection-limit than the quadrupole MS when operated in the EI-mode.
- Bergman, A.,Klasson Wehler, E.,Kuroki, H.,Nilsson, A.
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p. 1921 - 1938
(2007/10/03)
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