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- Danielsson, Conny, et al.
(författare)
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Comparison of Levels of PCDD/Fs and non-Ortho PCBs in PCB 153 from seven different suppliers
- 2008
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Ingår i: Organohalogen Compounds. ; 70, s. 001201-3
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Tidskriftsartikel (refereegranskat)abstract
- Twelve PCBs with dioxin-like (DL) properties have been carefully studied through the years to facilitate risk assessment and they have been assigned WHO-TEF values [1] based on their relative toxicity and endocrine effects compared to 2,3,7,8-TCDD. From a toxicological point of view, the non-dioxin-like PCBs (NDL-PCBs) are less characterized but usually account for more than 90% of the total mass of PCBs in food samples [2]. Furthermore, over 90% of the NDL-PCB exposure in the general population is via food and the average daily intake can be estimated to be 10-45 ng/kg (bw)/day according to the European Food Safety Authority EFSA [3]. The EFSA committee concluded that a proper risk assessment of this abundant and environmentally significant class of compounds could not be accomplished. In 2006, the European Commission initiated a project which has as its aim to better examine the toxicity of NDL-PCBs: ATHON- "Assessing the toxicity and hazard of nondioxin-like PCBs present in food". The ATHON project will perform all in vivo and in vitro studies with ultra pure PCBs with known levels of DL-PCBs, PCDD/Fs and total TEQ-levels. As a first step in this study the major suppliers of PCB 153 were identified and the aim of the research was to investigate if there were any clear differences in the quality of their products based on possible impurities of PCDD/Fs and non-ortho PCBs. PCB 153 was selected because of its relatively high presence in environmental compartments and biota and since it has been the most frequently studied NDL-PCB in a few major in vivo studies [2]. Impurities of PCDD/Fs and DL-PCBs, even at trace levels, in PCB 153 may make a significant contribution to the effects seen in in vivo studies as the highest concentrations being studied are at mg/g (bw)/day during a period of time. These high daily exposure levels in combination with possible accumulation of toxic impurities may by time pose a threat to the significance of observed effects. Within the ATHON project all NDL-PCBs used for both in vitro and in vivo tests are analyzed and in many cases purified to remove possible traces of PCDD/Fs and non-ortho PCBs.
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- Danielsson, Conny, 1977-
(författare)
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Trace analysis of dioxins and dioxin-like PCBs using comprehensive two-dimensional gas chromatography with electron capture detection
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), two groups of struc-turally related chlorinated aromatic hydrocarbons, generally referred to as “dioxins” are of great concern due to their extreme toxicity and presence in all compartments of the environment. Since they occur at very low levels, their analysis is complex and challenging, and there is a need for cost-efficient, reliable and rapid analytical alternatives to the expensive methods in-volving use of gas chromatography high-resolution mass spectrometry (GC-HRMS). It is im-portant to routinely monitor food and feed items to detect contaminations at an early stage. For the regulation of dioxins and dioxin-like PCBs in food and feed according to current legis-lation, large numbers of samples have to be analysed. Furthermore, soils at many industrial sites are also contaminated with dioxins and need remediation. In order to optimize the cost-efficiency of reclamation activities it is important to acquire information about the levels and distribution of dioxins in the contaminated areas. The aim of the studies underlying this thesis was to investigate the potential of comprehen-sive two-dimensional gas chromatography with a micro-electron capture detector (GC × GC-µECD) as a cost-effective method for analysing dioxins and dioxin-like PCBs in food, feed, fly ash and contaminated soils. Quantification studies of dioxins and dioxin-like PCBs were con-ducted and results were compared with GC-HRMS reference data. Generally, there was good agreement between both the congener-specific results and data expressed as total toxic equiva-lents (TEQs). The developed GC × GC-µECD method meets the European Community (EC) requirements for screening methods for control of dioxins and dioxin-like PCBs in food and feed. The presented results also indicate that GC × GC-µECD has potential to be used as a routine method for the congener-specific analysis of 2,3,7,8-PCDD/Fs and dioxin-like PCBs in matrices such as food and feed, fly ash and soil. However, to fully exploit the potential of the GC × GC-µECD technique, it should be combined with a fast and cost-efficient sample preparation procedure. Therefore, a number of certified reference materials (CRMs) were extracted using a new shape-selective pressurized liquid extraction technique with integrated carbon fractionation (PLE-C), and the purified extracts were analysed for PCDD/Fs using GC × GC-µECD. The results compared well with the certified values of a fly ash and a sandy soil CRM, but they were much too high for a com-plex clay soil CRM. It was concluded that this combination of techniques was very promising for screening ash and highly permeable soils. Further assessments and method revisions are still required before GC × GC-µECD can be used on a routine basis, and available software packages need to be refined in order to accelerate the data-handling procedures, which currently restrict the sample throughput.
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- Danielsson, Conny, et al.
(författare)
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Trace analysis of polychlorinated dibenzo-p-dioxins, dibenzofurans and WHO polychlorinated biphenyls in food using comprehensive two-dimensional gas chromatography with electron-capture detection
- 2005
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1086:1-2, s. 61-70
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Tidskriftsartikel (refereegranskat)abstract
- Trace analysis of 2,3,7,8-polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and the 12 WHO-PCBs (four non-ortho and eight mono-ortho congeners that have been assigned toxic equivalence factors, TEFs, by the World Health Organisation) was conducted by comprehensive two-dimensional gas chromatography with a micro electron-capture detector (GC x GC-mu ECD). Four food matrices (fish oil from herring, spiked cows' milk, vegetable oil and an eel extract) were analysed by two GC x GC laboratories, and four GC-HRMS laboratories generated reference values. The two GC x GC laboratories used different column combinations for separating the target analytes. For the first dimension, non-polar DB-XLB and VF-1 columns were used, and for the second dimension, an LC-50 liquid crystalline column with unique selectivity for planar compounds. The congener-specific and total toxic equivalence (TEQ) data obtained using DB-XLB x LC-50 were in good agreement with results obtained by the GC-HRMS laboratories. The WHO-PCB data obtained with the VF-1 x LC-50 combination was also good, but the PCDD/F concentrations were sometimes overestimated due to matrix interferences. GC x GC-mu ECD using DB-XLB x LC-50 seems to fulfil the European Community requirements of a screening method for PCDD/F and WHO-PCB TEQ in food.
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- Haglund, Peter, et al.
(författare)
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Effects of temperature and flow regulated carbon dioxide cooling in longitudinally modulated cryogenic systems for comprehensive two-dimensional gas chromatography
- 2002
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Ingår i: Journal of Chromatography A. ; 962:1-2, s. 127-34
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Tidskriftsartikel (refereegranskat)abstract
- Two different modes of temperature regulation in longitudinally modulated cryogenic systems (LMCSs) for comprehensive two-dimensional gas chromatography (GC×GC) were compared. Carbon dioxide was used as coolant. In the first mode of operation, the temperature of the trap was regulated to a pre-set temperature using a digital temperature controller (“the constant temperature mode”). In the second, the temperature was regulated to a fixed negative offset to the oven temperature by using a constant flow of CO2 (“the constant flow mode”). A number of problems were occasionally observed using the constant temperature mode: (1) severe band broadening of high boiling analytes in the second dimension; (2) non-Gaussian reconstructed first-dimension peak profiles; (3) high background due to modulation of first-dimension column bleed. It was concluded that these problems were associated with inefficient solute remobilization at low LMCS trap temperatures (1 and 2) or large trap temperature fluctuations (3). These problems could be avoided or significantly reduced by using the constant flow mode. Best results were obtained as the trap temperature was kept about 70 °C below the oven temperature.
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- Haglund, Peter, et al.
(författare)
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GCxGC-ECD a promising method for the determination of dioxins and dioxin-like PCBs in food and feed
- 2008
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Ingår i: Analytical and Bioanalytical Chemistry. - : Springer. - 1618-2642 .- 1618-2650. ; 390:7, s. 1815-1827
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for cost-efficient alternatives to gas chromatography (GC)–high-resolution mass spectrometry (HRMS) for the analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs) in food and feed. Comprehensive two-dimensional GC–micro electron capture detection (GC×GC-μECD) was tested and all relevant (according to the World Health Organisation, WHO) PCDD/Fs and PCBs could be separated when using a DB-XLB/LC-50 column combination. Validation tests by two laboratories showed that detectability, repeatability, reproducibility and accuracy of GC×GC-μECD are all statistically consistent with GC-HRMS results. A limit of detection of 0.5 pg WHO PCDD/F tetrachlorodibenzo-p-dioxin equivalency concentration per gram of fish oil was established. The reproducibility was less than 10%, which is below the recommended EU value for reference methods (less than 15%). Injections of vegetable oil extracts spiked with PCBs, polychlorinated naphthalenes and diphenyl ethers at concentrations of 200 ng/g showed no significant impact on the dioxin results, confirming in that way the robustness of the method. The use of GC×GC-μECD as a routine method for food and feed analysis is therefore recommended. However, the data evaluation of low dioxin concentrations is still laborious owing to the need for manual integration. This makes the overall analysis costs higher than those of GC-HRMS. Further developments of software are needed (and expected) to reduce the data evaluation time. Combination of the current method with pressurised liquid extraction with in-cell cleanup will result in further reduction of analysis costs.
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