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Distinguishing PCB Isomeric Congeners with their Gas Chromatographic and Mass Spectrometric Ortho Effect using Comprehensive Gas Chromatography
Osemwengie, L. Distinguishing PCB Isomeric Congeners with their Gas Chromatographic and Mass Spectrometric Ortho Effect using Comprehensive Gas Chromatography. Presented at Site Evaluation Tools and Emerging Technologies, Ashburn, VA, October 19 - 23, 2015.
This will be a poster presentation
The 209 polychlorinated biphenyl (PCB) congeners and associated nine isomeric groups (nine groups of PCBs with the same degree of chlorination) have been long recorded as high endocrine disrupting chemicals in the environment. Difficult analytical problems exist, in those frequent cases where several chromatographically coeluting (traversing the separation column simultaneously) PCB isomers or congeners are present in environmental samples. Analysts usually report final results in the form of “total PCB concentrations,” which only reflect a compromised or average value. In a case where a toxic PCB isomer coelutes with a non-toxic PCB isomer in environmental sample (a co-planar and non-coplanar, within isomeric group), total concentration of both isomers is reported because the toxic isomer could not be separated from the non-toxic one. This leads to enormous environmental remediation cost in hot spots for industries. Remediation may be avoided altogether if the toxic PCB isomers can be separated from the non toxic ones, and the actual concentration of the toxic PCB isomer ascertained to be below actionable level. This research work solved this problem by using two approaches. (1) Where the observable ortho effects or internal chemistry of the PCB isomers in question is used to distinguish one PCB isomer from the other. (2) The use of a newly introduced two-dimensional gas chromatography instrument for the front-end separation of several PCB congeners in ways never before possible. The issue of declorinated high mass PCB congeners, coeluting with low mass PCB congeners, is also resolved. This tool may be applied to other complex mixtures consisting of congeners and isomers, e.g., polybrominated biphenyls and toxaphene.