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New tools for sample preparation and instrumental analysis of dioxins in environmental samples
Umeå University, Faculty of Science and Technology, Department of Chemistry.
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), two groups of structurally related chlorinated aromatic hydrocarbons, are of high concern due to their global distribution and extreme toxicity. Since they occur at very low levels, their analysis is complex, challenging and hence there is a need for efficient, reliable and rapid alternative analytical methods. Developing such methods was the aim of the project this thesis is based upon.

During the first years of the project the focus was on the first parts of the analytical chain (extraction and clean-up). A selective pressurized liquid extraction (SPLE) procedure was developed, involving in-cell clean-up to remove bulk co-extracted matrix components from sample extracts. It was further streamlined by employing a modular pressurized liquid extraction (M-PLE) system, which simultaneously extracts, cleans up and isolates planar PCDD/Fs in a single step. Both methods were validated using a wide range of soil, sediment and sludge reference materials. Using dichloromethane/n-heptane (DCM/Hp; 1/1, v/v) as a solvent, results statistically equivalent to or higher than the reference values were obtained, while an alternative, less harmful non-chlorinated solvent mixture - diethyl ether/n-heptane (DEE/Hp; 1/2, v/v) – yielded data equivalent to those values.

Later, the focus of the work shifted to the final instrumental analysis. Six gas chromatography (GC) phases were evaluated with respect to their chromatographic separation of not just the 17 most toxic congeners (2,3,7,8-substituted PCDD/Fs), but all 136 tetra- to octaCDD/Fs. Three novel ionic liquid columns performed much better than previously tested commercially available columns. Supelco SLB-IL61 offered the best overall performance, successfully resolving 106 out of the 136 compounds, and 16 out of the 17 2,3,7,8-substituted PCDD/Fs. Another ionic liquid (SLB-IL111) column provided complementary separation. Together, the two columns separated 128 congeners. The work also included characterization of 22 GC columns’ selectivity and solute-stationary phase interactions. The selectivities were mapped using Principal Component Analysis (PCA) of all 136 PCDD/F’s retention times on the columns, while the interactions were probed by analyzing both the retention times and the substances’ physicochemical properties.

Place, publisher, year, edition, pages
Umeå: Umeå universitet , 2013. , 39 p.
Keyword [en]
PCDD/Fs, dioxins, pressurized liquid extraction, PLE, selective SPLE, modular M-PLE, soil, sediment, sludge, gas chromatography, new stationary phases, multivariate data analysis, selectivity, interaction
National Category
Environmental Sciences Analytical Chemistry
Research subject
biology, Environmental Science
URN: urn:nbn:se:umu:diva-70218ISBN: 978-91-7459-683-0 (printed)OAI: diva2:620383
Public defence
2013-06-05, KBC-huset, KB3A9, Umeå Universitet, Umeå, 09:00 (English)
Available from: 2013-05-15 Created: 2013-05-08 Last updated: 2013-05-15Bibliographically approved
List of papers
1. Optimization of selective pressurized liquid extraction for extraction and in-cell clean-up of PCDD/Fs in soils and sediments
Open this publication in new window or tab >>Optimization of selective pressurized liquid extraction for extraction and in-cell clean-up of PCDD/Fs in soils and sediments
2013 (English)In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 90, no 9, 2414-2419 p.Article in journal (Refereed) Published
Abstract [en]

This paper describes the development of methods for selective extraction of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) from soils and sediments, using pressurized liquid extraction with in-cell clean-up (SPLE). Two binary solvent mixtures, viz. dichloromethane/n-heptane (DCM/Hp), and diethylether/n-heptane (DEE/Hp), were evaluated. The SPLE extraction conditions were optimized using central composite face (CCF) design. Three factors were investigated: extraction temperature (60-160°C), number of extraction cycles (1-3) and time per cycle (2-18min). The results showed that DCM/Hp (1/1, v/v) and DEE/Hp (1/2, v/v) were the best extraction solvent compositions and that the extraction temperature was a critical factor that needed careful optimization to achieve high extraction efficiency without co-extraction of sulfuric acid. Under the optimal conditions, the SPLE methods provided results with good accuracy and precision. For the sandy soil certified reference material (CRM-529) the quantification results ended up in the range 82-110% as compared to the concentrations obtained by a reference method based on Soxhlet extraction and external column clean-up. Furthermore, for a clay soil (CRM-530) and a sediment reference material (WMS-01), the accuracy (trueness) of the TEQ values were +11% (DCM/Hp) and +8% (DEE/Hp) for CRM-530, +8% and -7% for WMS-01, respectively. The individual congener concentrations also agreed well with the certified values. These findings show that SPLE is a promising method for combined extraction and clean-up of PCDD/Fs in soil/sediment samples.

Place, publisher, year, edition, pages
Elsevier, 2013
Selective pressurized liquid extraction (SPLE), In-cell clean-up, Experimental design, PCDD/Fs, GC/HRMS, Soils and sediments
National Category
Chemical Sciences
urn:nbn:se:umu:diva-62027 (URN)10.1016/j.chemosphere.2012.10.070 (DOI)23177707 (PubMedID)
Available from: 2012-12-04 Created: 2012-12-04 Last updated: 2013-05-08Bibliographically approved
2. Modular pressurized liquid extraction for simultaneous extraction, clean-up and fractionation of PCDD/Fs in soil, sediment and sludge samples
Open this publication in new window or tab >>Modular pressurized liquid extraction for simultaneous extraction, clean-up and fractionation of PCDD/Fs in soil, sediment and sludge samples
2013 (English)In: Analytical Methods, ISSN 1759-9660, no 5, 1231-1237 p.Article in journal (Refereed) Published
Abstract [en]

Modular pressurized liquid extraction (M-PLE) procedures were developed for simultaneous extraction, clean-up and fractionation of polychlorinated dioxins and furans (PCDD/Fs) in soil, sediment and sludge samples. The procedures utilize two coupled extraction cells: an upstream cell filled with the sample and layers of silica and acid- and base-modified silica, and a downstream cell filled with activated carbon. The silica layers were added to remove polar or hydrolysable matrix components, and the carbon to perform planarity-based fractionation. Two solvent systems (dichloromethane–heptane, DCM–Hp and diethyl ether–heptane, DEE–Hp) and two activated carbon loads (1% and 3% carbon on Celite) were evaluated using certified reference materials (CRM-529 and WMS-01) and materials from previous inter-calibration studies. Using any of the four procedures, data statistically equivalent to the certified or reference values were obtained. The M-PLE procedure using DCM–Hp and 1% carbon sometimes extracted the reference materials more efficiently than the reference methods, while the DEE–Hp procedure extracted them equally efficient, offering an alternative with less environmental impact. The methods with 1% carbon on Celite produced sufficiently pure extracts for sample loads up to one gram, but for greater sample loads the higher carbon load (3% carbon on Celite) was required to avoid breakthrough of target analytes. The new streamlined procedures are fast, cost-efficient, involve relatively low environmental impact (in the case of DEE–Hp) and are well suited for high-throughput analysis of solid samples, e.g. in connection with environmental monitoring campaigns and major soil remediation efforts.

Place, publisher, year, edition, pages
RSC Publishing, 2013
National Category
Chemical Sciences
urn:nbn:se:umu:diva-66705 (URN)10.1039/C2AY26411K (DOI)
Available from: 2013-02-28 Created: 2013-02-28 Last updated: 2013-05-08Bibliographically approved

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