References of "De Pauw, Edwin"
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See detailMeasurement of Dioxins and WHO-PCBs in Foodstuffs using GCxGC-IDTOFMS
Focant, Jean-François ULg; De Pauw, Edwin ULg

Scientific conference (2004, December)

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See detailPerformances and limitations of the HRMS method for dioxins, furans and dioxin-like PCBs analysis in animal feedingstuffs Part I: Results of an inter-laboratory study
Eppe, Gauthier ULg; Cofino, W. P.; De Pauw, Edwin ULg

in Analytica Chimica Acta (2004), 519(2), 231-242

The European strategy for dioxin monitoring of the food chain has defined high-resolution gas chromatography coupled to high-resolution mass spectrometry (HRGC/HRMS) method as the confirmatory method that ... [more ▼]

The European strategy for dioxin monitoring of the food chain has defined high-resolution gas chromatography coupled to high-resolution mass spectrometry (HRGC/HRMS) method as the confirmatory method that can provide reliable and comparable results at sub-parts per trillion (ppt) level. This paper describes the first inter-laboratory study on dioxins, furans and dioxin-like PCBs by HRGC/HRMS method in animal feedingstuffs. Two different statistical approaches (ISO 5725 and Cofino's statistics) were used for the statistical evaluation. For this particular study, the performances of the HRGC/HRMS method seem to be congener-independent in repeatability and reproducibility conditions over a concentration range covering more than four orders of magnitude. Results clearly show the effect of precision loss below 0.1 ppt level per congener in repeatability conditions and below 0.2 ppt level per congener in reproducibility conditions. LODs reported by the laboratories give median values of 0.02 ng/kg for most of the toxic congeners. Relative standard deviation between the laboratories' mean values using upper-bound approach for TEQ calculation is 6.2%, more than twice the maximum level set at 0.75 ng TEQ/kg of product. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailPerformances and limitations of the HRMS method for dioxins, furans and dioxin-like PCBs analysis in animal feedingstuffs Part II: Does it comply with the European pro-active approach?
Eppe, Gauthier ULg; Maghuin-Rogister, Guy ULg; De Pauw, Edwin ULg

in Analytica Chimica Acta (2004), 519(2), 243-253

Based on the results obtained from the inter-laboratory study in Part 1, different approaches for detection and quantification limits are evaluated and discussed. An overview of the most commonly used ... [more ▼]

Based on the results obtained from the inter-laboratory study in Part 1, different approaches for detection and quantification limits are evaluated and discussed. An overview of the most commonly used concepts and terminologies in analytical chemistry is presented with the aim of establishing a link between them. Whatever the method used by laboratories for detection limit assessment, the median LOD value reported for the less chlorinated PCDD/Fs (i.e. 0.02 ng/kg) is in good agreement with the values recalculated using the inter-laboratory data. For LOQ the Eurachem approach based on a pre-established percentage of repeatability RSD appears to be. suitable. The study shows that a pre-established RSDr of 20% is recommended in order to achieve an acceptable LOQ of 0.05 ng/kg per congener. The 20% value seems to be sufficiently low to act tolerable RSD close to maximum limits. Furthermore, the repeatability and the reproducibility standard deviation against parts-per-trillion congener levels has been modeled by inverse first order functions. This congener precision model provides an interesting tool to subsequently assess the performances of the method in TEQ close to regulatory limits. Finally, the paper discusses two different ways of reporting and interpreting the results to assess compliance against statutory limits. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailAutomated sample preparation-fractionation for the measurement of dioxins and related compounds in biological matrices: a review
Focant, Jean-François ULg; Pirard, Catherine; De Pauw, Edwin ULg

in Talanta (2004), 63(5), 1101-1113

This article reviews some of the recent developments in the extraction and clean-up areas of biological samples dedicated to dioxin and related compound analysis. A brief introduction on the major dioxin ... [more ▼]

This article reviews some of the recent developments in the extraction and clean-up areas of biological samples dedicated to dioxin and related compound analysis. A brief introduction on the major dioxin contamination events, which have occurred in the food chain, is given to illustrate the need of fast high throughput methods in case of crises. The emphasis of this paper is the method development based upon reliable instrumental extraction techniques for rapid sample processing and automation such as; supercritical fluid extraction (SFE), microwave-assisted extraction (MAE), pressurized liquid extraction (PLE) and, solid-phase extraction (SPE). The PLE and SPE are also discussed in conjunction with the use of a multi-column automated clean-up system that can accommodate up to 5 g of extracted lipids. The fractionation in sub-groups of analytes during the clean-up process allows the isolation of various types of toxicants from a single sample and illustrates the versatility of the system. An integrated extraction and clean-up instrument is finally presented in terms of feasibility and attainable sample turnover for the parallel processing of liquid and solid biological samples. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailValidation of the CALUX bioassay for PCDD/F analyses in human blood plasma and comparison with GC-HRMS
Van Wouwe, N.; Windal, I.; Vanderperren, H. et al

in Talanta (2004), 63(5), 1157-1167

Following the dioxin crisis of 1999, several studies were conducted to assess the impact of this crisis on the dioxin body burden in the Belgian population. The Scientific Institute of Public Health ... [more ▼]

Following the dioxin crisis of 1999, several studies were conducted to assess the impact of this crisis on the dioxin body burden in the Belgian population. The Scientific Institute of Public Health identified a population from whom plasma samples were available and from whom, during the follow up survey, plasma samples were obtained in 2000. In total, 496 samples were collected for GC-HRMS and CALUX analyses to verify statistical assessment conclusions. This study was seen as an opportunity to validate the CALUX bioassay for biological sample analysis and to compare toxic equivalency (TEQ) values obtained by the reference GC-HRMS technique and by the screening method. This article focuses on the validation results of the CALUX bioassay for the analyses of the dioxin fractions of blood plasma. The sample preparation is based on a liquid-liquid extraction, followed by an acid silica in series with an activated carbon clean-up. A good recovery (82%) and reproducibility (coefficient of variation less than 25%) were found for this method. Based on 341 plasma samples, a significant correlation was established between the bioassay and chemical method (R = 0.64). However, a proportional systematic error was observed when the results obtained with the CALUX bioassay were regressed with the results from the GC-HRMS analyses. The limit of quantification (LOQ) used to calculate TEQ values from the GC-HRMS determinations, the use of the relative potency values instead of the toxic equivalent factor and the potential of CALUX bioassay to measure all compounds with affinity for the AhR may partly explain this proportional systematic error. Nevertheless, the present results suggest that the CALUX bioassay could be a promising valid screening method for human blood plasma analyses. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailImportance of clean-up for comparison of TEQ-values obtained by CALUX and chemo-analysis
Van Wouwe, N.; Windal, I.; Vanderperren, H. et al

in Talanta (2004), 63(5), 1269-1272

This paper presents Chemically Activated LUciferine gene eXpression (CALUX) TEQ-values obtained for nine plasma samples following two different purification procedures, one of them involving fractionation ... [more ▼]

This paper presents Chemically Activated LUciferine gene eXpression (CALUX) TEQ-values obtained for nine plasma samples following two different purification procedures, one of them involving fractionation. CALUX results obtained for the dioxin (DX) and dioxin + PCB (DX + PCB) fractions were then compared to the GC-HRMS TEQ-values calculated for the 17 polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (17 PCDD/F) and 17 PCDD/F + 4 cPCB congeners, respectively. The overestimation of the CALUX (DX fraction) TEQ-values in comparison with the chemo-analyses of the 17 PCDD/F is mainly explained by the presence of other AhR agonists, like brominated compounds. Otherwise, the constancy of the CALUX (DX + PCB fraction) TEQ-value which compares to increasing the GC-HRMS (17 PCDD/F + 4 cPCB) TEQ results raises questions concerning (1) the significance of CALUX results obtained without fractionation as well as (2) the toxicological effect of a cocktail of contaminants on the human health. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailA strategy to identify specific biomarkers related to the effects of a PCDD/F mixture on the immune system of marine mammals
Brenez, C.; Gerkens, P.; Mazzucchelli, Gabriel ULg et al

in Talanta (2004), 63(5), 1225-1230

The cell lines chosen have demonstrated a positive response in terms of cell proliferation and associated modifications in proteins content, evaluated through DNA and proteins synthesis, at ... [more ▼]

The cell lines chosen have demonstrated a positive response in terms of cell proliferation and associated modifications in proteins content, evaluated through DNA and proteins synthesis, at environmentally relevant dose of dioxins, brought by a typical environmental PCDD/F mixture. The response is time and species dependent. After completion of the identification of proteins affected by the intoxication, we will identify a set of specific proteins whose expression is correlated to the dioxin dose and submit the cell culture to the treatment with a single chemical as well as with mixtures. We hope that this will allow us to construct and validate a set of protein biomarkers of exposure to pollutants that will show a predictive aspect for unknown chemicals. The quantitative analysis of the set of biomarkers can then be a more specific bioassay and an alternative to physico-chemical or other already established bioanalytical methods for screening purposes. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailAutomated extraction and clean-up system for liquid materials
Focant, Jean-François ULg; De Pauw, Edwin ULg

Scientific conference (2004, April)

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See detailAutomated extraction and clean-up system for solid materials
Focant, Jean-François ULg; De Pauw, Edwin ULg

Scientific conference (2004, April)

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See detailLevels of PCDDs, PCDFs and PCBs in Belgian and international fast food samples
Focant, Jean-François ULg; Pirard, Catherine; De Pauw, Edwin ULg

in Chemosphere (2004), 54(1), 137-142

Congener-specific analyses of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) were performed on twenty-eight non-pooled fast food ... [more ▼]

Congener-specific analyses of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) were performed on twenty-eight non-pooled fast food samples collected in Belgium, Switzerland, Czech Republic, United States of America and Australia. PCDD/F and PCB concentrations for the four investigated types of meals were very low. PCDD/F values ranged from non-detected to 1.40 pg WHO-TEQ/g fat and from 0.79 to 2.08 pg WHO-TEQ/g fat for lower and upper bound, respectively. Major contributors to the PCDD/F TEQ were 1,2,3,4,7,8-HxCDD, 1,2,3,6,7,8-HxCDD, 2,3,7,8-TCDF and 2,3,4,7,8-PeCDF. The relative contribution of PCBs to the total TEQ was 68%. For adults, an average estimated intake was 6.7 pg WHO-TEQ/kg bw/month, including consumption of all types of analyzed meals, representing 9.5% of the PTMI. For child, a value of 14.5 pg WHO-TEQ/kg bw/month was obtained, representing 20.6% of the PTMI. (C) 2003 Elsevier Ltd. All rights reserved. [less ▲]

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See detailIdentification of specific biomarkers related to the effects of pollutants on the immune system of marine mammals
Brenez, Cécile; Gerkens, Pascal; Jauniaux, Thierry ULg et al

Poster (2004)

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See detailHigh-throughput analysis of human serum for selected polychlorinated biphenyls (PCBs) by gas chromatography-isotope dilution time-of-flight mass spectrometry (GC-IDTOFMS)
Focant, Jean-François ULg; Cochran, Jack W.; Dimandja, Jean-Marie D. et al

in Analyst (2004), 129(4), 331-336

A method for the high-throughput analysis of human serum for the 38 most prevalent polychlorinated biphenyls (PCBs) based on the use of fast gas chromatography-isotopic dilution time-of-flight mass ... [more ▼]

A method for the high-throughput analysis of human serum for the 38 most prevalent polychlorinated biphenyls (PCBs) based on the use of fast gas chromatography-isotopic dilution time-of-flight mass spectrometry (GC-IDTOFMS) is presented. The chromatographic separation time was 8 min. The separation of the congeners was carried out either chromatographically or analytically using the mass spectral deconvolution capability of the TOFMS. The instrument and the method limits of detection (LODs) were 0.5 pg muL(-1) and 20 pg muL(-1), respectively, which is not as good as the one achieved using high resolution mass spectrometry (HRMS) but allows the detection and quantification of the prevalent PCBs present in real human serum samples. The dynamic range covered 3 orders of magnitude. The comparison with the high resolution mass spectrometry (HRMS) reference method (28 min) was good and some separation improvements have been observed. This method allows the analysis of 100 samples per day per instrument. [less ▲]

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See detailContribution of tobacco smoking to dioxin accumulation: opposite effects according to gender
Fierens, Sébastian; Eppe, Gauthier ULg; Focant, Jean-François ULg et al

in Organohalogen Compounds (2004), 66

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See detailMeasurement of dioxins and WHO PCBs in foodstuffs using GCxGC-IDTOFMs
Focant, Jean-François ULg; Pirard, Catherine; Massart, Anne-Cécile ULg et al

in Organohalogen Compounds (2004), 66

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See detailAssessment of the impact of an old MSWI. Part1 : Level of PCDD/Fs and PCBs in surrounding soils and eggs
Pirard, Catherine; Focant, Jean-François ULg; Massart, Anne-Cécile ULg et al

in Organohalogen Compounds (2004), 66

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See detailDR-CALUX((R)) screening of food samples: evaluation of the quantitative approach to measure dioxin, furans and dioxin-like PCBs
Scippo, Marie-Louise ULg; Eppe, Gauthier ULg; De Pauw, Edwin ULg et al

in Talanta (2004), 63(5), 1193-1202

European legislation laid down maximum tolerable levels of dioxin in feed and food as well as analytical method requirements. In order to face with large monitoring programs, it was foreseen in the EU ... [more ▼]

European legislation laid down maximum tolerable levels of dioxin in feed and food as well as analytical method requirements. In order to face with large monitoring programs, it was foreseen in the EU strategy to integrate screening methods, using either a qualitative (screening) approach, or a quantitative approach. In this study, dioxin results obtained using the Dioxin Responsive Chemical-Activated LUciferase gene eXpression (DR-CALUX(R)) cell-based assay (quantitative approach), were compared with gas chromatography-high resolution mass spectrometry (GC-HRMS) analyses data. Instead of using World Health Organization-toxic equivalent factor (WHO-TEF), the comparison was based on the assessment of relative effective potencies (REPs) for each congener of the 17 toxic 2,3,7,8-polychlorodibenzo-p-dioxins/furans (PCDD/Fs) and 12 dioxin-like polychlorobiphenyls (DL-PCBs). According to published data, DR-CALUX(R)-REP evaluated here appear similar to WHO-TEF for PCDD/Fs while lower values were observed for DL-PCBs. We analyzed two "home made" contaminated fat samples, displaying both the same WHO-toxic equivalent quantities (WHO-TEQ) concentration (12 pg WHO-TEQ g(-1)). They were spiked with either a low or a high amount of DL-PCBs. In both cases, the DR-CALUX(R) measured concentration (picogram 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) eq. g(-1)) corresponded to the PCDD/Fs WHO-TEQ concentration only. A good agreement was nevertheless found between the DR-CALUX(R) measurements and the recalculated DR-CALUX(R)-TEQ contents (using DR-CALUX(R)-REP instead of WHO-TEF), demonstrating that the observed response was due, in both cases, to the addition of the responses of the standards added to the fat. By contrast, in real contaminated samples (feed or cod liver samples), DR-CALUX(R) measured concentrations were similar to WHO-TEQ GC-HRMS measured concentrations. But, depending on the PCDD/Fs and DL-PCBs congener content, the DR-CALUX(R) measured concentrations were either lower or higher than calculated DR-CALUX(R)-TEQ contents, demonstrating that possible co-extracted contaminants contributed to the CALUX response. Owing to these divergences, the quantitative determination of dioxin-like content in food and feed using CALUX as screening method is questionable, except for samples displaying constant congener patterns, in which cases, correction factors could be applied. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailInvestigation of non-covalent interactions between paramagnetic complexes and human serum albumin by electrospray mass spectrometry
Henrotte, Virginie; Laurent, Sophie ULg; Gabelica, Valérie ULg et al

in Rapid Communications in Mass Spectrometry : RCM (2004), 18(17), 1919-1924

Stable gadolinium(III) chelates are nowadays routinely used as contrast agents for magnetic resonance imaging (MRI). Their non-covalent binding to human serum albumin (HSA) has shown to improve their ... [more ▼]

Stable gadolinium(III) chelates are nowadays routinely used as contrast agents for magnetic resonance imaging (MRI). Their non-covalent binding to human serum albumin (HSA) has shown to improve their efficacy. Non-covalent interactions lead to complex formation that can be quantified by several techniques that are mostly tedious and time-consuming. In this study, electrospray ionization mass spectrometry (ESI-MS) was used to investigate the interaction between HSA and several gadolinium(III) complexes. The results were compared with those obtained in the liquid phase. Four gadolinium complexes were investigated: Gd-DTPA 1, Gd-C4Me-DTPA 2, Gd-EOB-DTPA 3, and MP-2269 4. Relaxometry studies show that complexes 1 and 2 have no significant affinity for HSA, while complexes 3 and 4 have increasing affinities for the protein. 1:1 and 1:2 complexes between HSA and MP-2269 were detected by ESI-MS for a twofold excess of the contrast agent, whereas a ligand/protein molar ratio of 4:1 was necessary to observe a 1:1 stoichiometry for Gd-EOB-DTPA, an observation that is in good agreement with the known weaker affinity of the contrast agent for the protein. At a fourfold molar excess, no supramolecular complex was observed for Gd-DTPA I and Gd-C4Me-DTPA 2; a tenfold molar excess was necessary to detect a 1:1 complex, confirming the very weak affinity of these contrast agents for HSA. [less ▲]

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