Deciphering the Code of Dibenzodioxins (dioxins) and Dibenzofurans (furans)
Dioxins and Furans are toxic compounds that are persistent in the environment and can have severe health effects if not monitored. This has researchers wondering how the compounds originate and the best way to monitor the variety of analogues associated with them. Within environmental testing, “dioxins” and “furans” specifically refer to polychlorinated dibenzodioxins (PCDD compounds) and polychlorinated dibenzofurans (PCDF compounds). These compounds are persistent organic pollutants (POP compounds) that have an affinity for a transcription factor protein named Aryl-Hydrocarbon Receptor.
We will not be diving into dioxin like compounds such as dioxane, dioxin, furan, or tetrahydrofuran(THF) even though these compounds could be found during a typical round of testing. However, I want to solely focus on the importance of dioxin and furan testing. Discussions about POPs among environmental chemists can seem like a secret club to newcomers. Especially given the range of assumed background knowledge and awareness of the “secret code” by which these compounds are referred.
PCDD dioxin pollutants have a storied background and are historically known as biproducts of the production. These include herbicides as 2,4,5-T (Trichlorophenoxyacetic acid) and 2,4-D (Dichlorophenoxyacetic acid), which together comprise Agent Orange. These herbicides themselves have a toxicity profile, but the dioxin biproducts are far more toxic.
Dioxin biproducts were not initially monitored during the production or use of herbicides due to a lack of awareness of the intense toxicity of PCDD compounds. Historically relevant large-scale usage and industrial accidents involving these herbicides have resulted in persistent environmental contamination with dioxins.
During the synthesis of polychlorinated phenyl herbicides, a critical intermediate is polychlorinated phenolate. This can be prone to side-reactions that produce PCDD compounds. Polychlorinated phenols themselves are pesticides that may generate PCDDs. Today, both PCDD and PCDF pollutants are monitored as biproducts of the incomplete combustion of garbage, which can be found at single households or larger quantities of garbage intended for landfills.
Isotopic analysis may be used to correlate results of dioxins with the source or location where PCDD or PCDF originated. PCDF “furan” pollutants may result from a variety of oxidative reactions towards polychlorinated biphenyl (PCB) compounds. PCB compounds themselves are toxic and are common dielectric compounds used within electrical capacitors, leading to their pervasiveness in landfills.
The phrase, “I am trying to separate my 1238 from my 2378″ might sound crazy when heard out of context. However, hasn’t everyone been a little guilty of lockdown madness during this year?
We can make sense of this by first numbering the positions around our dibenzo compounds to which chlorines may bond. Notice that the tertiary carbons are not numbered. Be careful as to when you are discussing PCDD and PCDF compounds.
The next consideration is the prefix that denotes the number of chlorines that are bonded to the dibenzo compound. Environmental methods are typically concerned with PCDD and PCDF compounds with four or more chlorine substituents (see Table 1). The “octa-chlorinated” analogues do not require numbering, as all of the substituent positions are bonded with a chlorine substituent.
PCDD and PCDF compounds are often referred to by the nomenclature demonstrated in Table 1. There are occasions during routine testing when these compounds refer to the position of the chlorine substituents, such as separating a 1238 from a 2378. The context specifically pertains to either PCDD compounds or PCDF compounds, especially when speaking with members of other laboratories or organizations.
It is important to thank the chemists and laboratory technicians who are monitoring environmental samples for PCDD and PCDF compounds, along with related herbicide and PCB compounds. Their work is protecting overall human health from exposures to dioxins and keeping us safe from these invisible threats. Hopefully we have dispelled the ambiguity that may surround “dioxin and furan” analysis for any newcomers to the topic.
Have any questions regarding dioxin and furan troubleshooting, analysis, or monitoring? You can speak directly with the author of this article, Zachary Woodward, through Phenomenex’s free online support service. With a 24/7 global team, our Technical Experts are here for you any time a problem might arise in the lab. Reach out to our team today through Chat Now for exceptional technical assistance.
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Zebron ZB-Dioxin columns are specifically tailored for the analysis of dioxins and furans in Food and Environmental matrices. Tetra dioxins and furans are highly toxic and requires fast and reliable analysis. Currently many analysis’ are time consuming and require two GC columns and two GC-HRMS instruments. This new GC innovation is proven to be a single solution that plays a major role in testing productivity and throughput.
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Phenomenex offers a wide range of educational and technical resources available at your fingertips! Explore our library of free webinars and seminars today at www.phenomenex.com/webinars. See the following webinars as a potential kickoff to exploring our webinar library.
Gas Chromatography Webinar – “Exploring Fast GC Solutions for Priority Pollutants like PAH and PCB in Food and Environmental Samples.”
If this article was helpful and of interest, then there is so much more for you to explore. Discover articles covering a diverse amount of technical and trending topics today. There are even more by your favorite guest author, Zachary Woodward, like “Gas Chromatography Basics – Constant Pressure, Constant Flow, and Constant Confusion.“