Characterizing All 136 Tetra- to Octachlorinated Dioxins and Furans
Using the Rtx-Dioxin2 Column
- Known elution orders for all tetra- through octachlorinated dioxin and furan congeners.
- Resolve 14 of 17 tetra- through octachlorine 2,3,7,8-substituted dioxins and furans.
- TCDD and TCDF specificity, with a column stable up to 340°C.
Successful analyses of dioxins and furans are critical because of the extremely toxic nature of these compounds. However, confidently resolving the most toxic congeners, 2,3,7,8-substituted tetrachlorinated dibenzodioxin (TCDD) and tetrachlorinated dibenzofuran (TCDF), is often complicated by the presence of the many other possible congeners. Even with high resolution GC/high resolution MS methods, the proper choice of chromatographic column is essential for separating 2,3,7,8-substituted dioxins and furans from the less toxic congeners and matrix-related compounds.
Complete Column Characterization
It is rare that a column’s performance is characterized against all possible 136 tetra- through octachlorinated dioxins and furans. These standards are difficult to obtain, and testing can be time consuming. However, here the Rtx-Dioxin2 column is characterized against all 136 compounds using standards from Cambridge Isotope Laboratories, Inc. When compared to industry standard stationary phases, a unique selectivity is observed for the Rtx-Dioxin2 column, and specific resolutions and coelutions are noted. Very few coelutions involving the toxic 2,3,7,8-substituted congeners are observed, making the Rtx-Dioxin2 column an excellent choice for single column analyses of dioxins and furans. (Tables I and II - click images below to enlarge)
Figure 1 shows fly ash samples, run under the same chromatographic conditions used to characterize the column. 2,3,7,8-tetrachlorodibenzofuran is not resolved under these conditions. However, the characterization study used simple linear temperature programming, and additional work exploring nonlinear oven programs and different flow parameters yielded better resolution between some congeners, especially 2,3,7,8-TCDF (data available upon request). The value in this work is not necessarily to show complete separation of all the congeners on a single column, but to show where all of the 136 compounds of interest elute, making all possible coelutions known.
The Rtx-Dioxin2 column is an excellent column for the analysis of dioxin and furan congeners. It has a unique selectivity for the toxic congeners, including specificity for 2,3,7,8-TCDD and 2,3,7,8-TCDF. Here we characterized all 136 tetra- through octachlorine dioxins and furans and defined all possible coelutions. While commonly used cyanopropyl columns are limited by a low maximum operating temperature of 240°C, the Rtx-Dioxin2 column is stable up to 340°C, extending column lifetime and improving analyses of dioxins and furans.
Table I Retention times (RT) and relative retention times (RRT) for all tetra- through octachlorinated dioxins on an Rtx-Dioxin2 column. Click image below to enlarge
RRTs were calculated versus 12378 13C-labeled dioxin.
Table II Retention times (RT) and relative retention times (RRT) for all tetra- through octachlorinated furans on an Rtx-Dioxin2 column.Click image below to enlarge
RRTs were calculated versus 12378 13C-labeled furan.
*Note that the 1289 tetrachlorinated congener elutes after the 13468 pentachlorinated congener.
Figure 1 GC/HR-MS analysis of tetrachlorinated dioxins in fly ash on an
Figure 2 GC/HR-MS analysis of tetrachlorinated furans in fly ash on an