IP10 Emerging Issues in Analytical Chemistry
B115 & B116
1:20 PM - 4:40 PM, Wednesday
(IP082) Which PCB congeners are needed to estimate total PCBs in aquatic biota?
Nedoff, J1, Kennedy, L1, Williams, B2, 1 Kennedy/Jenks Consultants, San Francisco, CA, USA2 Kennedy/Jenks Consultants, Portland, OR, USA
ABSTRACT- PCBs can be measured by quantifying against technical Aroclor® mixtures or individual congeners. In tissue samples, the patterns detected do not match the Aroclor® mixtures due to the effects of weathering and metabolism, and congener analysis is a more accurate representation of total PCBs. Because there are 209 individual congeners, this analysis often results in much higher analytical costs than Aroclor® analysis. To reduce costs, shorter lists of representative congeners are developed. A variety of PCB congener lists have been used at sediment sites, including a list developed by NOAA for the National Status and Trends Program. If a short list of congeners can be defined that consistently represents a proportion of the total, laboratories could adopt this list for analysis, resulting in reduced costs. This would also result in comparable datasets at sediment sites where PCBs are the focus. The total from the short list could be multiplied by a defined factor to determine the total PCB concentration. To develop a proposed "short list," datasets from a variety of sites that include an extensive list of congeners in tissue samples were analyzed to determine the most abundant congeners among various tissue types. This analysis resulted in a list of congeners that represents a consistent proportion of the total PCB value. This list was compared to the NOAA list, the list of dioxin-like congeners, and other "short lists" of congeners analyzed at sediment sites. The summed concentration of the 12 dioxin-like congeners and the associated TEQ also are compared to the estimated total PCB concentration for the different tissue types. Potential savings in project costs are also presented.
Key words: congeners, PCBs, tissue, analysis