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Evaluation of Comprehensive 2-D Gas Chromatography-Time-Of-Flight Mass Spectrometry for 209 Chlorinated Biphenyl Congeners in Two Chromatographic Runs
Citation:
OSEMWENGIE, L. I. AND G. SOVOCOOL. Evaluation of Comprehensive 2-D Gas Chromatography-Time-Of-Flight Mass Spectrometry for 209 Chlorinated Biphenyl Congeners in Two Chromatographic Runs. CHROMATOGRAPHY RESEARCH INTERNATIONAL. SAGE-Hindawi Access to Research , London, Uk, 2011:1-14, (2011).
Impact/Purpose:
Chlorinated biphenyls (CBs), or polychlorinated biphenyls (PCBs), are comprised of 209 distinct chlorine-substituted biphenyl structures (congeners). Ten isomeric groups of congeners exist with varying degrees of chlorination (see Table I). Approximately 140 to 150 of the 209 PCB congeners listed in Table II, were found in the complex mixtures (Aroclors) that were used commercially in a variety of applications, including heat transfer and hydraulic fluids, dielectric fluids for capacitors, and as additives in pesticides, sealants, and plastics [1-3]. The dispersion of PCB congeners in the form of the Aroclors by uncontrolled release into the environment, their long-term stability, and possible toxicity, together caused concern for their biological and environmental impact. The World Health Organization (WHO) designated twelve PCBs as “dioxin-like, co-planar PCB congeners” that exhibited high toxicity [4]. Originally, the noncoplanar PCBs were considered the most toxic because they were present in much greater abundances. Later, the “coplanar” PCBs were found to have dioxin-like toxicity, and received the most attention. It appears that the toxicity of the noncoplanar PCBs has been re-emphasized because most noncoplanar congeners with ortho chlorine substitution were also found to be toxic in mammalian brains [5-7].
Description:
This research evaluates a recently developed comprehensive 2-D GC coupled with a time-of-flight (TOF) mass spectrometer for the potential separation of 209 PCB congeners, using a sequence of 1-D and 2-D chromatographic modes. In two consecutive chromatographic runs, using a 40 m, Rtx-PCB column and a 1 m DB-17 column, connected in tandem, 196 PCB congeners are distinguished, including 43 of the 46 pentachlorobiphenyl isomers. Some of the chlorinated biphenyls that could not be resolved chromatographically are resolved with the use of the “ortho effect,” which distinguishes PCB isomers having 2,2‟-; and 2,2‟6- chlorine substitution from those isomers without these substitutions. The result of this work falls short of our goal of separating all 209 PCB congeners, but still provides investigators with a new tool for a better front-end separation of PCB-specific congeners, and potentially, for use in acquisition of more accurate data.