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PLE with integrated clean up followed by alternative detection steps for cost-effective analysis of dixons and dioxin-like compounds
Umeå University, Faculty of Science and Technology, Chemistry.
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are two structurally related groups of chemicals, generally referred to as `dioxins´. These are of great concern due to their high toxicity and global spread. Other groups of compounds with similar chemical structure and toxicity mechanisms are the brominated analogues polybrominated dibenzo-p-dioxins (PBDDs) and polybrominated dibenzofurans (PBDFs), and the dioxin-like polychlorinated biphenyls (PCBs). Numerous studies have been undertaken to investigate sources and transport routes of dioxins. However, much remains to be done, including analytical, inventories of dioxin-like compounds, such as PBDD/Fs, and the development of more convenient analytical methods. The currently standard procedure for analyzing dioxins (and dioxin-like compounds) is to use Soxhlet extraction followed by multi-step clean-up and gas chromatography - high resolution mass spectrometry (GC- HRMS) for detection. Unfortunately, this method is very solvent, labor and time-consuming, making it very expensive.

The main aim of the studies this thesis was to develop pressurized liquid extraction (PLE) with integrated clean up techniques for fast, convenient preparation of dioxin samples. PLE with integrated clean-up has previously been used for extracting dioxins from biological samples, but in these studies the possibility of extending its use to abiotic samples was explored. The results show that PLE with an integrated carbon trap is suitable for analyzing dioxins in various types of soil samples, sediment and flue gas samples. The results also showed that it has potential for analyzing dioxins in fly ash. The thesis focuses on developments of the methodology for dioxin analysis, but also includes results obtained from PBDDs and dioxin-like PCB analyses. In addition, the possibility of using various other kinds of detection techniques rather than GC-HRMS, such as enzyme-linked immunosorbent assays (ELISAs) or two-dimensional gas chromatography with micro electron capture detection (GCxGC-µECD) was explored. The results indicate that ELISA and GCxGC-µECD could serve as complementary detection systems in some cases. However, it is not yet possible to fully replace GC-HRMS.

A further refinement of the PLE with in-cell clean-up technique is the modular approach developed in these studies. With this technique it is possible to include various steps for both clean-up and fractionation. For example, sulphuric acid impregnated silica could be combined with active carbon for the simultaneous removal of lipids (along with other interferences) and fractionation of PCBs and PCDD/Fs. It was shown that the method could provide data that agreed reasonably well with both reference values and values obtained using traditional methods. In general PLE proved to have high extraction efficiency and to yield very similar congener profiles to the reference method. In addition, it was shown that it allowed one-step extraction and clean-up of a salmon sample. Such single-step procedures are the ultimate goals for any extraction technique, and it would be highly desirable to develop one-step methods that could be extended to other types of samples. For the rest of the matrices tested (soil, sediment, mussel and crab tissue and flue gas) the method was successful, however a final polishing step is currently required, involving either dilution or clean-up using miniaturized multilayer silica columns, to obtain extracts that are pure enough for GC-HRMS analysis.

Using the developed modular-PLE system substantial costs could be saved. It was estimated that the method could reduce the cost of preparing samples by up to 90%, which would greatly facilitate large-scale inventories.

Place, publisher, year, edition, pages
Umeå: Kemi , 2008. , 37 p.
Keyword [en]
Pressurized liquid extraction (PLE), PLE-C, modular PLE, ELISA, dioxin, dioxin-like compounds, GCxGC, analytical methods
National Category
Environmental Sciences
Identifiers
URN: urn:nbn:se:umu:diva-1665ISBN: 978-91-7264-584-4 (print)OAI: oai:DiVA.org:umu-1665DiVA: diva2:141751
Public defence
2008-06-13, N360, Naturvetarhuset, Umeå, 13:00 (English)
Opponent
Supervisors
Available from: 2008-05-19 Created: 2008-05-19 Last updated: 2009-07-02Bibliographically approved
List of papers
1. Rapid screening of dioxin-contaminated soil by accelerated solvent extraction/purification followed by immunochemical detection
Open this publication in new window or tab >>Rapid screening of dioxin-contaminated soil by accelerated solvent extraction/purification followed by immunochemical detection
Show others...
2006 (English)In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 385, no 2, 357-366 p.Article in journal (Refereed) Published
Abstract [en]

Since soils at industrial sites might be heavily contaminated with polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), there is a need for large-scale soil pollution surveys and, thus, for cost-efficient, high-throughput dioxin analyses. However, trace analysis of dioxins in complex matrices requires exhaustive extraction, extensive cleanup, and very sensitive detection methods. Traditionally, this has involved the use of Soxhlet extraction and multistep column cleanup, followed by gas chromatography-high-resolution mass spectrometry (GC/HRMS), but bioanalytical techniques may allow much more rapid, cost-effective screening. The study presented here explores the possibility of replacing the conventional method with a novel approach based on simultaneous accelerated solvent extraction (ASE) and purification, followed by an enzyme-linked immunosorbent assay (ELISA). Both the traditional and the novel cleanup and detection approaches were applied to contaminated soil samples, and the results were compared. ELISA and GC/HRMS results for Soxhlet-extracted samples were linearly correlated, although the ELISA method slightly underestimated the dioxin levels. To avoid an unacceptable rate of false-negative results, the use of a safety factor is recommended. It was also noted that the relative abundance of the PCDDs/PCDFs, evaluated by principal component analysis, had an impact on the ELISA performance. To minimize this effect, the results may be corrected for differences between the ELISA cross-reactivities and the corresponding toxic equivalency factor values. Finally, the GC/HRMS and ELISA results obtained following the two sample preparation methods agreed well; and the ELISA and GC/HRMS results for ASE extracts were strongly correlated (correlation coefficient, 0.90). Hence, the ASE procedure combined with ELISA analysis appears to be an efficient approach for high-throughput screening of PCDD-/PCDF-contaminated soil samples.

Place, publisher, year, edition, pages
Springer Science+Business Media B.V., 2006
Keyword
Immunoassay, ELISA, Soil, Dioxin, Accelerated solvent extraction
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-11789 (URN)10.1007/s00216-006-0402-9 (DOI)16598456 (PubMedID)
Available from: 2007-08-17 Created: 2007-08-17 Last updated: 2013-09-09Bibliographically approved
2. Rapid and cost-effective analysis of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in soil, fly ash and sediment certified reference materials using pressurized liquid extraction with an integrated carbon trap.
Open this publication in new window or tab >>Rapid and cost-effective analysis of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in soil, fly ash and sediment certified reference materials using pressurized liquid extraction with an integrated carbon trap.
2008 (English)In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, Vol. 390, no 1, 411-417 p.Article in journal (Refereed) Published
Abstract [en]

Pressurized liquid extraction with an integrated carbon trap (PLE-C) has recently been developed for fast and efficient analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in food and feed. The method has also been tested, but not verified, for use on more complex soil samples, such as soil, sediment and fly ash. Hence, the primary aim of this study was to verify that PLE-C can produce reliable data for PCDDs/PCDFs in various abiotic matrixes. A second aim was to find a replacement for the previously used AX21 active carbon that is currently not commercially available. The performance of the PLE-C was evaluated using both single congener concentrations and toxic equivalency potentials (TEQ-pot) of three (soil, sediment and fly ash) certified reference materials. The results clearly show that PLE-C can be used for abiotic samples and that a commercially available carbon (Norit SA 4PAH HF) can replace the AX-21 carbon in the carbon trap. The TEQ-pot values obtained for the soil and sediment samples were within the uncertainty limits of the corresponding certified values, as were the determinations of single congener concentrations. PLE-C therefore has great potential for determination of PCDDs/PCDFs in soil and sediment samples. The TEQ-pot result for the fly ash was slightly lower than the certified TEQ-pot value, but it is still within the uncertainty limits of the certified value. Out of the single congener concentrations all but four (out of 17) agreed well with the values. Hence, PLE-C may potentially be used also for fly ash-after slight modifications. The integrated PLE-C and cleanup procedure is less labour-intensive than traditional methods such as Soxhlet extraction followed by a multistep cleanup, and consumes smaller quantities of ultrapure solvents than the commonly used Power-Prep system. In addition, PLE-C is capable of larger sample throughputs than the conventional methods. Thus, PLE-C is a promising alternative to the currently used sample preparation procedures for dioxins in abiotic samples. Figure PLE with integraded carbon trap for rapid PCDD/Fs analysis.

Keyword
Pressurized liquid extraction, Dioxins, Certified reference materials, In-cell cleanup, Solid samples
Identifiers
urn:nbn:se:umu:diva-5981 (URN)doi:10.1007/s00216-007-1696-y (DOI)17994226 (PubMedID)
Available from: 2007-12-27 Created: 2007-12-27Bibliographically approved
3. Analysis of dioxins in soil and fly ash using pressurized liquid extraction with an integrated carbon trap followed by comprehensive two-dimensional gas chromatography with electron capture detection
Open this publication in new window or tab >>Analysis of dioxins in soil and fly ash using pressurized liquid extraction with an integrated carbon trap followed by comprehensive two-dimensional gas chromatography with electron capture detection
(English)Manuscript (preprint) (Other (popular science, discussion, etc.))
Identifiers
urn:nbn:se:umu:diva-3232 (URN)
Available from: 2008-05-19 Created: 2008-05-19 Last updated: 2010-01-14Bibliographically approved
4. Streamlined Combustion Gas Measurements for Improved National Dioxin Inventories
Open this publication in new window or tab >>Streamlined Combustion Gas Measurements for Improved National Dioxin Inventories
2008 (English)In: Environmental Science & Technology, Vol. 42, no 24, 9255-61 p.Article in journal (Refereed) Published
Abstract [en]

The analysis of PCDD/Fs requires advanced analytical instruments and is a complex, labor intensive process that consumes large quantities of high-purity solvents. It is therefore very expensive and thus problematic-or even impossible-for developing countries to afford to establish reliable PCDD/F source inventories in support of global and national emission reduction strategies. Low-cost reliable alternatives are needed to improve this situation. Therefore, a streamlined procedure for flue gas sampling and analysis has been developed and evaluated that utilizes a user-friendly polyurethane foam plug (PUFP) sampling technique. The collected samples are then shipped to a central laboratory for analysis where they are processed using a cost-efficient pressurized liquid extraction procedure with in-cell carbon cleanup (PLE-C) prior to analysis by gas chromatography-high-resolution mass spectrometry (GC-HRMS). The PLE-C technique has previously been validated for a range of matrices, and, in the present study, has been further improved by introducing an extraction cell coupling cartridge. The entire procedure was evaluated using three sets of samples: two from a laboratory-scale incinerator and one from a full-scale incinerator. The samples were expected to differ in PCDD/F levels and homologue patterns. Each sample was split and analyzed in parallel by both PLE-C and a reference procedure (Soxhlet extraction followed by a traditional multistep cleanup procedure, Sox-T). The results of analysis by PLE-C compared well with those from analysis by Sox-T. The difference between toxic equivalent (TEQ) values obtained using the PLE-C and reference technique for 11 PUFP samples ranged from -10% to +44% and the two techniques also yielded very similar PCDD/F homologue profiles. A principal component analysis (PCA) of the data showed that both methods were able to discriminate among the three sets of samples, thereby demonstrating that the between method variability was less than the between-sample variability. In summary, the results indicate that PUFP sampling followed by PLE-C extraction and cleanup provides a fast, relatively cheap, and reliable method for analysis of PCDD/Fs in flue gas.

Identifiers
urn:nbn:se:umu:diva-11308 (URN)doi:10.1021/es801187n (DOI)
Available from: 2008-12-15 Created: 2008-12-15 Last updated: 2010-01-19Bibliographically approved
5. Modular Pressurized liquid extraction for combined extraction and clean up of dioxin-like PCBs, PBDD and PCDD/Fs
Open this publication in new window or tab >>Modular Pressurized liquid extraction for combined extraction and clean up of dioxin-like PCBs, PBDD and PCDD/Fs
(English)Manuscript (preprint) (Other (popular science, discussion, etc.))
Identifiers
urn:nbn:se:umu:diva-3234 (URN)
Available from: 2008-05-19 Created: 2008-05-19 Last updated: 2010-01-14Bibliographically approved

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