References of "Focant, Jean-François"
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See detailMedical Application: Breath Volatile Compounds in Asthma Patients
Stefanuto, Pierre-Hugues ULiege; Zanella, Delphine ULiege; dejong, Thibaut et al

Scientific conference (2019, June)

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See detailColorectal Cancer : Biomarkers and Effect Size
Di Giovanni, Nicolas ULiege; Meuwis, Marie-Alice ULiege; Louis, Edouard ULiege et al

Poster (2019, May 21)

Colorectal cancer kills more than 700.000 persons each year worldwide. Nevertheless, its diagnosis is still largely based on invasive tissue sampling and gaps remain in the understanding of its ... [more ▼]

Colorectal cancer kills more than 700.000 persons each year worldwide. Nevertheless, its diagnosis is still largely based on invasive tissue sampling and gaps remain in the understanding of its pathogenesis, with complex combinations between lifestyle, genetics, epigenetics, chronic inflammation (IBD) and microbiota. We analyzed serum samples from patients affected by colorectal cancer (CRC, n = 18) and by colorectal cancer in remission (R-CRC, n = 17), and samples from healthy patients matched for biases (HC, n = 19 and R-HC, n = 17). The aim was to find candidate biomarkers able to diagnose the active state of the disease as well as to compare the concentration levels of the molecules of interest with the remission state to better understand the biolocal processes beneath the observed clinical and metabolic symptoms. To do so, an optimized and validated (NIST SRM 1950) comprehensive GC×GC-(HR)TOFMS method we developed was used. It includes an in-house QC system, data processing based on multiple statistical techniques and identification using full mass spectrum, linear retention indices and accurate mass provided by state-of-the-art high-resolution (HR) time-of-flight mass spectrometry. Because the experimental design prevented a direct comparison between the active and remission samples, which were not directly matched for biases, we used a measure called effect size that has the advantage to not only focus on statistical significance but on effect (here signal variation) magnitude. We will discuss the interest and application of effect size in metabolomics and we will present the highlighted candidate biomarkers in terms of discrimination potential. [less ▲]

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See detailOptimizing of TD-GC×GC-HRTOFMS for the profiling of cannabis blends
Dubois, Lena ULiege; Ledent, Maxime ULiege; Franchina, Flavio ULiege et al

Poster (2019, May 13)

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See detailIn vitro characterization of lung inflammation mechanisms
Zanella, Delphine ULiege; Dejong, Thibaut; SCHLEICH, FLorence ULiege et al

Poster (2019, May 13)

Exhaled breath analysis has a high potential for early non-invasive diagnosis of lung conditions. Most of lung diseases involve a certain level of inflammation. The characterization of the ongoing ... [more ▼]

Exhaled breath analysis has a high potential for early non-invasive diagnosis of lung conditions. Most of lung diseases involve a certain level of inflammation. The characterization of the ongoing inflammation processes is crucial to define proper medication. The inflammation processes are associated with oxidative stress, which yields to the conversion of chemical from the membranes (as polyunsaturated fatty acids) into volatile compounds secreted by the lungs1. The understanding of the metabolic pathways involved in volatile markers production could open new therapeutic routes for inflammatory diseases. In this study, the lung inflammation was simulated in vitro. A549 epithelial cells, originally isolated from human alveoli, were cultured with and without oxidative agents (from chemical or biological origins) as part of a discovery study for lung inflammation mechanisms characterization. The cell culture volatile organic compounds (VOCs) were extracted by solid phase micro-extraction (SPME) and thermal desorption (TD) and analyzed by comprehensive two-dimensional gas chromatography hyphenated to time-of-flight mass spectrometers (GC×GC-TOFMS). The complete analytical workflow was optimized using central composite design model. On the processing side, different models were designed to compare the volatile profile of the epithelial cells in different inflammatory conditions. Univariate and multivariate feature selection approaches, i.e. Fisher Ratio and Random Forest, were then used to identify specific inflammatory markers. Based on the output, cross-comparison with metabolic pathways databases (e.g. KEGG) was performed. This work is setting up the basis of a multimodal and biomedical project on lung inflammation characterization. [less ▲]

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See detailUnit duty-cycle differential flow modulation GC×GC-MS: insights on the modulation process
Franchina, Flavio ULiege; Zanella, Delphine ULiege; Weggler, Benedikt ULiege et al

Poster (2019, May)

One of the major limitations of current-day flow-modulated comprehensive two-dimensional gas chromatography (FM GC×GC) is the generation of high gas flows (e.g., 20 mL/min) in the second analytical ... [more ▼]

One of the major limitations of current-day flow-modulated comprehensive two-dimensional gas chromatography (FM GC×GC) is the generation of high gas flows (e.g., 20 mL/min) in the second analytical dimension, if unit sampling duty cycle is considered [1]. Even though such high flows are necessary to efficiently flush the content of the modulator onto the second dimension, they also greatly restrict the employment of mass spectrometry (MS), which is nowadays considered as the most powerful and informative detection tool. One way to enable the use of MS systems, in FM applications, is to divert a substantial part of the second-dimension flow to waste, with an obvious negative impact on sensitivity. The present contribution is focused on the development of unit sampling duty cycle methods using flow-modulated comprehensive two-dimensional gas chromatography in combination with mass spectrometry. Specifically, a FM GC×GC-MS approach was developed in which the flows necessary to efficiently flush the modulator were greatly reduced (<5 mL/min) [2]. The approach finely reconsiders the accumulation and injection phases of modulation and allows a full transfer onto the second dimension and the detector with no need to divert the flow [3]. The efficiency of the set-up is demonstrated on real-world samples (petrochemical and fragrance). [less ▲]

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See detailImplementation of GC×GC-qMS/FID for VOC profiling in the forensic sciences
Perrault, Katelynn ULiege; Cernosek, Terezie; Byrne, Julienne et al

Conference (2019, May)

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See detailBidimensional gas-chromatography (GCxGC-ToF-MS) to evaluate the volatile profile of grappa
Betnega, P; Longo, E; de Matos, A et al

Poster (2019, May)

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See detailComprehensive Approach for Monitoring Human Tissue Degradation
Dubois, Lena ULiege; Stefanuto, Pierre-Hugues ULiege; Perrault, Katelynn ULiege et al

in Chromatographia (2019)

In recent years, comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC–TOFMS) has been reported as a suitable tool for the determination of volatile organic ... [more ▼]

In recent years, comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC–TOFMS) has been reported as a suitable tool for the determination of volatile organic compounds (VOCs) emitted during the process of cadaveric decomposition. The main aim of the present study was to investigate temporal changes in VOC patterns during the decomposition process of various human tissues. The focus of previous research was mainly on the analysis of VOCs produced by whole cadavers. However, this study aimed to identify whether the VOCs produced during decomposition differ between specific organs, and further, to determine the extent of the variation between cadavers. The sampling process developed for this project allowed inter- and intra-cadaveric comparison. The headspace of heart, lung, liver, kidney and blood was monitored during the decomposition process. Tissue samples from five different cadavers were sampled regularly by dynamic pumping onto sorbent tubes that were further thermally desorbed onto a GC × GC–TOFMS system. A large amount of data (n = 774) was obtained, leading to challenges in the integration, interpretation and representation of the results. Eventually, multivariate statistical methods, such as principal components analysis (PCA) and hierarchical cluster analysis (HCA) were applied to the dataset to evaluate trends and differences in subgroups. It was demonstrated that there were subtle differences between the sets of compounds produced from each organ due to the different functions they carry out within the body. However, VOC profiles were more similar among organs from the same cadaver than when comparing samples from different cadavers. Various reasons may cause the differences between the analyzed cadavers, ranging from the individual diet and lifestyle to the time since death. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature. [less ▲]

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See detailMolecular characterization of petroleum mixtures using multiple ionization modes and GC×GC-HRTOFMS
Stefanuto, Pierre-Hugues ULiege; Giri, Anupam; Courtiade, Marion et al

Poster (2019, May)

Introduction: Comprehensive two-dimensional gas chromatography (GC×GC) has become a method of choice for complex mixture characterization, especially in the petroleum industry. Indeed, the high resolving ... [more ▼]

Introduction: Comprehensive two-dimensional gas chromatography (GC×GC) has become a method of choice for complex mixture characterization, especially in the petroleum industry. Indeed, the high resolving power of the 2D separations offers structured separation allowing pattern recognition and group type classification of sample composition. For years, the technique was relying on electron ionization (EI) fragmentogram and chromatographic-based identification due to practical limitations on the detector side, mainly the high acquisition frequency required. The development of high-speed high-resolution time-of-flight mass spectrometers (TOFMS) offers opportunities to go deeper in the sample characterization. To obtain the most of the HRMS dimension, there is a growing interest to combine EI with softer ionization techniques, which preserve the molecular ion. Method: In this study, different base oil samples and standard mixtures were analyzed by GC×GC-HRTOMS. Three different soft-ionization techniques including photo ionization (PI), chemical ionization (CI), and field ionization (FI) were compared against EI to elucidate their relative capabilities to reveal different base oil hydrocarbon classes. Deeper investigations were also conducted on the PI fragmentation process for different chemical families. All the experiments were performed on a single system, a JEOL AccuTOF GCv 4G with modular ionization technologies. A low-polar (ZB-XLB-HT Inferno, 15.0 m, 0.25 mm ID, 0.1 μm, Phenomenex ) and polar (ZB-50HT, 2.0 m, 0.1 mm ID, 0.1 μm, Phenomenex) columns were used for base oil analysis for first and second dimension separation respectively. Preliminary Data: Compared to EI (70 eV), capabilities and limitations of PI were tested using an authentic mixture of compounds of several chemical classes. Ionization energy exhibited by PI, equivalent to 10.8 eV, resulted in significant retention of molecular ion information; [M]+• for alkanes, ketones, FAMEs, aromatics, [M−H]+• for chloroalkanes, and [M−H2O]+• for alcohols. In addition, considering the potential of PI for hydrocarbons, base oils, complex mixtures of saturated and unsaturated hydrocarbons blended for finished lubricant formulations, were extensively evaluated. PI retained significant molecular ion (M+‧) information for a large number of isomeric species including branched-alkanes and saturated mono-cyclic hydrocarbons along with unique fragmentation patterns. However, for bi-/poly cyclic naphthenic and aromatic compounds, EI played upper hand by retaining molecular as well as fragment ions to identify the species, whereas PI exhibited mainly molecular ion signals. CI revealed selectivity towards different base oil groups, particularly for steranes, sulfur-containing thiophenes, and esters; yielding protonated molecular ions (M+H) + for unsaturated and hydride abstracted ions (M-H+) for saturated hydrocarbons. FI, as expected, generated intact molecular ions (M+‧) irrespective to the base oil chemical classes. It allowed elemental composition by TOFMS with a mass resolving power up to 8,000 (FWHM) and a mass accuracy of 1 mDa, leading to the calculation of heteroatomic content, and carbon number of the compounds. The qualitative and quantitative results presented herein offer a unique perspective into the detailed comparison of different ionization techniques corresponding to several chemical classes. Novel aspect: The GC×GC field is ongoing a paradigm shift in which the MS dimension is even further contributing than before. [less ▲]

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See detailPhenotypage de l'asthme par volatilomique de l'haleine
Zanella, Delphine ULiege; Stefanuto, Pierre-Hugues ULiege; SCHLEICH, FLorence ULiege et al

Conference (2019, March 26)

L’asthme est l’une des maladies inflammatoires chroniques les plus répandues dans le monde, touchant 235 millions de personnes. Cela représente un problème majeur de santé publique dû aux coûts élevés ... [more ▼]

L’asthme est l’une des maladies inflammatoires chroniques les plus répandues dans le monde, touchant 235 millions de personnes. Cela représente un problème majeur de santé publique dû aux coûts élevés, estimés à 19,3 milliards d’euros par an, liés au traitement et au diagnostic. L’asthme est caractérisé par différents mécanismes inflammatoires des voies respiratoires. En fonction du profil inflammatoire, le traitement le plus adapté sera différent. C’est pourquoi, les traitements actuels ne sont pas efficaces pour une majorité des patients. Le développement de méthode pouvant caractériser efficacement les différents types d’asthme (éosinophilique, neutrophilque, paucigranulocytique, mixte-granulocytique) permettrait l’établissement de traitement personnalisé. L’utilisation de l’haleine comme outils de diagnostic permettrait l’établissement d’une procédure non-invasive pour le suivi de l’asthme. Dans cette étude, nous avons analysé les composés organiques volatils provenant de l’haleine de 521 patients. Les échantillons ont été collectés dans des sacs Tedlar®. Cette étude a été réalisée en deux phases cliniques. La chromatographie gazeuse couplée à la spectrométrie de masse (GC-MS) a été utilisée lors de la première phase. Sept composés ont été identifiés comme marqueurs potentiels de l’asthme par utilisation d’algorithmes d’apprentissage automatique. La phase de validation a été réalisée en analysant l’haleine de 245 patients par chromatographie gazeuse bidimensionnelle exhaustive couplée à la spectrométrie de masse à haute résolution (GC×GC-HRTOFMS). Cette phase de validation a confirmé l’efficacité de cinq composés. L’utilisation des indices de rétention, de la haute résolution et de l’injection de standards internes ont permis l’identification robuste des composés cibles. Dans les deux phases cliniques, les courbes ROC (receiver operating characteristic) ont été construites pour évaluer la performance de la classification dans un scénario de classification binaire. Chaque cohorte de patients a été divisée en un deux sets : un set d’apprentissage servant à la construction du modèle statistique et un set de validation. La phase clinique de validation a confirmé l’efficacité de cinq composés pour la classification des patients sur base de leur phénotype avec une précision de 70%, 60% et 64%. Ces molécules cibles fonctionnent mieux que les méthodes classiques de diagnostiques basées sur l’analyse sanguine ou du NO. La combinaison des analyses sanguines, de mesure du NO et des molécules volatiles cibles fournit la meilleure performance de classification avec une précision de 76%. Cette étude représente la première étude clinique à grande échelle dans le domaine des méthodes de diagnostic basée sur l’haleine. Elle a permis l’identification de marqueurs permettant le phénotypage des patients asthmatiques. Cette étude démontre le potentiel de l’analyse d’haleine pour le diagnostic clinique. [less ▲]

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See detailImportance du type d'absorbant pour l'échantillonnage des volatils : application sur les cultures bactériennes et l'haleine
Zanella, Delphine ULiege; Franchina, Flavio ULiege; Stefanuto, Pierre-Hugues ULiege et al

Poster (2019, March)

Les composés organiques volatils bactériens (VOC) sont considérés comme des biomarqueurs sensibles et spécifiques pour le phénotypage bactérien dans les biofluides humains (haleine, sang, urine, etc.) et ... [more ▼]

Les composés organiques volatils bactériens (VOC) sont considérés comme des biomarqueurs sensibles et spécifiques pour le phénotypage bactérien dans les biofluides humains (haleine, sang, urine, etc.) et dans les milieux de culture. La possibilité d'utiliser les VOCs pour l'identification bactérienne ouvre de nouvelles possibilités pour la mise au point de techniques de diagnostiques plus efficaces. Outre les différences biologiques des environnements in-vivo et in-vitro, il est essentiel d'utiliser la même technique d’échantillonnage pour la caractérisation et la validation de biomarqueurs. Dans cette étude, la chromatographie gazeuse bidimensionnelle couplée à la spectrométrie de masse (GC×GC-MS) a été utilisée pour comparer et évaluer différents adsorbants de tubes de désorption thermique pour l’échantillonnage des VOCs. Plus précisément, les paramètres suivants ont été évalués pour chaque adsorbant: sensibilité, sélectivité, reproductibilité et linéarité. Cinq adsorbants différents (Carbopack Y, X, B, Carboxen 1000 et Tenax), utilisés individuellement ou en combinaison, ont été testés sur un mélange de standards (15 composés). Les meilleures sensibilité et reproductibilité ont été obtenues pour les tubes conditionnés avec du Tenax. Les deux tubes de désorption thermique les plus performants, Tenax et Carbopack Y + X + Carboxen 1000, ont également été évalués sur des cultures de E. coli, S. aureus et P. aeruginosa. Ces deux types de tubes ont pu distinguer les 3 types de culture bactérienne, mais une amélioration de la sensibilité et de la reproductibilité a été obtenue avec les tubes Tenax. Une comparaison similaire sur les performances des tubes a été effectuée sur des échantillons d'haleine. [less ▲]

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See detailDioxin testing will soon be five times more sensitive
Focant, Jean-François ULiege

in LabInsights (2019)

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See detailDéveloppement et validation d'une méthode de diganostique non-ciblée pour la caractérisation des fluides pulmonaires
Zanella, Delphine ULiege; Stefanuto, Pierre-Hugues ULiege; Dubois, Lena ULiege et al

Poster (2019, March)

L’amélioration constante de l’instrumentation analytique génère un intérêt croissant dans les études métabolomiques. Dans ce contexte de caractérisation de mélanges complexes, la chromatographie gazeuse ... [more ▼]

L’amélioration constante de l’instrumentation analytique génère un intérêt croissant dans les études métabolomiques. Dans ce contexte de caractérisation de mélanges complexes, la chromatographie gazeuse bidimensionnelle (GC×GC) constitue une solution efficace pour obtenir un aperçu complet de la composition des échantillons. Cependant, l’augmentation de la résolution analytique s'accompagne d'une augmentation de la complexité des données générées [1,2]. Pour garantir l'utilisation correcte de l'instrumentation analytique, l’optimisation de la méthode et l’établissement d’un protocole de contrôle qualité (QC) adéquats et clairement définis sont nécessaires. Malheureusement, peu d'études GC×GC non ciblées présentent ces aspects importants et une utilisation abusive des termes validation et semi-quantification est florissante dans les publications. Ces biais conduisent au problème général du manque de reproductibilité des études en science, souligné dans les publications récentes de Nature [3,4]. Pour résoudre ce problème, plusieurs initiatives, telles que l'initiative de normalisation en métabolomique (MSI), ont établi des directives générales pour éviter ce manque de robustesse analytique [5,6].Cette étude présente l'application et l'adaptation des directives MSI pour l'analyse de mélanges volatils à l'aide de la GC×GC-TOFMS. Pour illustrer cette approche, les profils volatils de fluide de lavage bronchoalvéolaire (BALF) ont été analysés. Cette procédure médicale est largement répandue et fournit des informations importantes sur les processus immunologiques, inflammatoires et infectieux des voies respiratoires. Tout d'abord, une solution de QC a été créée en regroupant des échantillons de BALF provenant de différents patients. Cette solution a ensuite été utilisée pour l’optimisation de la méthode, c’est-à-dire l’échantillonnage ainsi que les conditions chromatographiques. Sur base des conditions optimales, la validation a été effectuée. La solution QC a également été utilisée comme base pour la mise en œuvre d'un protocole de contrôle de qualité pour l'analyse de volatils dans les matrices biologiques. Cette étude a pour objectif de fournir des conseils pour l’établissement d’une stratégie analytique robuste pour les analyses non ciblées. References 2. Stefanuto, P. H. et al. Advanced method optimization for volatile aroma profiling of beer using two-dimensional gas chromatography time-of-flight mass spectrometry. J. Chromatogr. A 1507, 45–52 (2017). 3. Monya Baker. Seek out stronger science. Nature 537, 703–704 (2016). 5. Sumner, L. W. et al. Proposed minimum reporting standards for chemical analysis: Chemical Analysis Working Group (CAWG) Metabolomics Standards Initiative (MSI). Metabolomics 3, 211–221 (2007). [less ▲]

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See detailUse of Blood Volatiles as Trace Evidence
Dubois, Lena ULiege; Perrault, Katelynn ULiege; Stefanuto, Pierre-Hugues ULiege et al

Poster (2019, February 20)

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See detailGCxGC coupled to TOFMS: A powerful tool for complex applications in Separation Science
Focant, Jean-François ULiege

Scientific conference (2019, February)

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