Organic Chemistry Section
Environmentally Persistent Contaminants

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Mass Spectrometry Department | Ambient Air Analysis | PCBs and Pesticides in Tissue & Wildlife | PCBs and Pesticides in the Human Population | Safe Drinking Water Act | Sediments and Soils | PCB Congeners | Emerging Contaminants | Low Level PCBs and Pesticides in Surface Water

Polychlorinated Biphenyl Congeners Polychorinated biphenyls (PCBs) are a complex group of industrial chemicals, whose properties were useful because of their resistance to degradation. This resistance means they are present in almost all aspects of the environment. Because of their ability to withstand degradation, these chemicals persist in the environment and will tend to bioaccumulate in animal and human tissues. Several of the specific components (or congeners) in various PCB mixtures have been found to exhibit varying degrees of toxicity. In order to assess the possible toxicity of the matrix being examined, it is becoming more and more important to isolate these individual congeners. Currently the WSLH is testing for approximately one hundred and one (101) congeners represented by seventy-five (75) chromatographic peaks which includes some of the coplanar ("toxic") congeners (see below). The extraction techniques vary according to the matrix (see method summaries) but the analysis techniques are the same. Analysis of these congeners is performed using capillary gas chromatography and electron capture detection (GC/ECD). Calibration is done using the 1994 Mullin mix of Aroclors 1232, 1248, and 1262.

The WSLH has developed the ability to analyze for these compounds in a variety of environmental matrices at the part per billion, part per trillion and even sub-part per trillion levels. Analysis can be done on soil and sediment, water and effluent, human serum, and a multitude of wildlife (e.g., fish, mink, eagle, duck, bear, etc.).

Polybrominated Diphenyl Ethers (PBDEs)

Polybrominated diphenyl ethers are a complex group of chemicals used predominantly by the flame retardant industry. Like PCBs these chemicals resist degradation in the environment and have shown a tendency to bioaccumulate in animal and human tissues. However these compounds have not undergone an exhaustive examination, in the way that PCBs have, and much more study is needed to determine their effect on the environment.

The WSLH Organic Chemistry Section has participated in research projects with a number of others including the University of Wisconsin - Madison, the Wisconsin Department of Health and Family Services and the WDNR. Currently (November 2003) we are working with WDNR toxicologists to study the effect of PBDEs on cormorant reproduction and to study their prevalence in sediment and wastewater treatment plant effluent.

At this time we are looking for approximately 10 of the PBDE congeners. Many of the techniques used for PCB analysis are adaptable to the analysis of PBDEs and we currently have or are developing methods for these contaminants in similar matrices (e.g., soil, sediment, water, effluent, human serum, and wildlife).

Multi-Dimensional Gas Chromatography

The WSLH has also refined its capability for testing fish and wildlife tissue and soil and sediment for PCB congeners by the use of a Siemens "heartcutting" or multi-dimensional GC/ECD. The system uses two chromatographic columns and a switching technique to separate the components of interest from the rest of the congeners. This technique is used for testing for seven (7) coplanar ("toxic") congeners that either coelute with other congeners using traditional capillary GC or they are nonexistent or small components in the Mullin Aroclor standard mix. For this testing pure analytical standards for each congener are used. At the present time, the laboratory is only testing for these seven congeners, but this technique can be developed for other congeners as needed.

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Last updated 11/13/03