Polychlorinated Dibenzo-p-Dioxins and Polychlorinated Dibenzofurans (PCDD/Fs)

HxCDD_F

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are common contaminants at historical contaminated sites. PCDD/Fs are generally referred to as “dioxins” although the name is technically incorrect, it has been used so much that it has stuck. PCDD/Fs are a group of 210 different structural congeners that are not produced intentionally as by-products of numerous processes. You can find basic information on PCDD/Fs structures and nomenclature on my blog (http://chemistry-matters.com/dioxins-and-furans-101/). PCDD/Fs are unwanted by-products of incineration processes, uncontrolled burning and certain industrial processes. Chemistry Matters has specialty knowledge in the industrial processes resulting in the formation of PCDD/Fs, especially from historical chemical manufacturing.

Although 210 congeners exist, only 17 congeners are reported as part of standard PCDD/F analysis using EPA methods 8290 and 1613. These 17 congeners are considered the toxic congeners due to the presence of chlorine in the 2, 3, 7, and 8 positions. These positions are important for the toxicity mediated endpoint of binding with the Ah receptor. These congeners are also the ones monitored as part of biomonitoring projects. In addition to these 17 congeners, the total amount of congeners in each of the chlorine groups (also known as homologues) – tetra, penta, hexa, hepta groups are also reported. An example of a chromatogram for hexachlorinated dioxins and furans is shown in the figure below which shows the hexa congeners that are 2378 substituted as well as the other congeners found in the homologue group.

Using all the congeners would be better for environmental forensics investigations to determine source, the 17 congeners and total homologue data can be normalized to provide graphical images of the PCDD/F patterns in a sample. These normalizing and graphical techniques are commonly used for visualization for environmental forensics investigations.

Chemistry Matters Inc has vast experience in the analysis and data interpretation of PCDDs and PCDFs in all environmental and biological matrices as part of biomonitoring and environmental forensics investigations.