This method is for the determination of 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (2,3,7,8-TCDD), 2,3,7,8-tetrachlorinated dibenzofuran (2,3,7,8-TCDF), and the 2,3,7,8-substituted penta-, hexa-, hepta-, and octachlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in water at part-per-trillion (ppt) concentrations. The sample is filtered prior to extraction to remove particulates. The filtrate is extracted with methylene chloride using a separatory funnel, liquid-liquid extractor or solid phase extraction (SPE). The particulates are extracted separately with toluene using a Soxhlet extractor. After extraction C13-labeled standards are spiked into the sample to monitor clean-up efficiency. Clean-up options for the extracts are an acid-base wash, gel permeation, alumina, silica gel and Florisil column clean-ups. After clean-up the extract is concentrated and analyzed by high resolution gas chromatography/low resolution mass spectrometry (HRGC/LRMS).
This is an isotope dilution method.
A calculation of the TEQ (toxicity equivalent concentration) is done for each sample using international toxicity equivalency factors (TEFs). A high TEQ, greater than 7 ppt, will require analysis on a second GC column unless 2,3,7,8-TCDF is separated from its closest eluting isomers from analysis on the primary column.
This method replaces Methods 8280 and 8280A.
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| Hold Times, Preservatives, Preps, Collection, Analytical & Documentation | |
|---|---|
| Holding Time: | 30 days from collection to extraction and 45 days from extraction to analysis. |
| Preservatives: | Cool to ≤ 6°C. If residual chlorine is present, add 80 mg sodium thiosulfate per liter of sample. If pH > 9, adjust to pH 7-9 with sulfuric acid. |
| Required Preps: | 1L amber glass bottle |
| Collection Method: | Grab sampling, SW-846 Chapter 4 |
| Analytical Methodology: | HRGC/LRMS |
| Documentation: | 
8280B
|
* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.