References of "Focant, Jean-François"
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See detailBreathomics to diagnose systemic sclerosis using thermal desorption and comprehensive two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry
Zanella, Delphine ULiege; GUIOT, Julien ULiege; Stefanuto, Pierre-Hugues ULiege et al

in Analytical and Bioanalytical Chemistry (2021)

Systemic sclerosis is a rare autoimmune disease associated with rapidly evolving interstitial lung disease, responsible for the disease severity and mortality. Specific biomarkers enabling the early ... [more ▼]

Systemic sclerosis is a rare autoimmune disease associated with rapidly evolving interstitial lung disease, responsible for the disease severity and mortality. Specific biomarkers enabling the early diagnosis and prognosis associated with the disease progression are highly needed. Volatile organic compounds in exhaled breath are widely available and non-invasive and have the potential to reflect metabolic processes occurring within the body. Comprehensive two-dimensional gas chromatography coupled to high-resolution mass spectrometry was used to investigate the potential of exhaled breath to diagnose systemic sclerosis. The exhaled breath of 32 patients and 30 healthy subjects was analyzed. The high resolving power of this approach enabled the detection of 356 compounds in the breath of systemic sclerosis patients, which was characterized by an increase of mainly terpenoids and hydrocarbons. In addition, the use of 4 complementary statistical approaches (two-tailed equal variance ttest, fold change, partial least squares discriminant analysis, and random forest) resulted in the identification of 16 compounds that can be used to discriminate systemic sclerosis patients from healthy subjects. Receiver operating curves were generated that provided an accuracy of 90%, a sensitivity of 92%, and a specificity of 89%. The chemical identification of eight compounds predictive of systemic sclerosis was validated using commercially available standards. The analytical variations together with the volatile composition of room air were carefully monitored during the timeframe of the study to ensure the robustness of the technique. This study represents the first reported evaluation of exhaled breath analysis for systemic sclerosis diagnosis and provides surrogate markers for such disease. [less ▲]

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See detailComparison of headspace solid-phase microextraction high capacity fiber coatings for untargeted analysis of beer volatiles using GC-MS/VUV
Zanella, Delphine ULiege; Anderson, Hailee E.; Selby, Talena et al

Poster (2021, March 12)

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See detailGC×GC-TOFMS for boar taint volatolomics
Dubois, Lena ULiege; Delhaye, Myriam; Mayeres, Patrick et al

Poster (2021, January)

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See detailImpact of the adsorbent material on volatile metabolites during in vitro and in vivo bio-sampling
Franchina, Flavio ULiege; Zanella, Delphine ULiege; Dejong, Thibaut ULiege et al

in Talanta (2021)

The increased attraction of biological volatile compounds has opened the route to a wide variety of sampling techniques, amongst which trap tubes packed with adsorbent materials are commonly used. Many ... [more ▼]

The increased attraction of biological volatile compounds has opened the route to a wide variety of sampling techniques, amongst which trap tubes packed with adsorbent materials are commonly used. Many types of adsorbent materials are available and the choice of the adsorbent can impact the obtained results in untargeted analysis. Therefore, a proper combination of the adsorbent material and the sample is necessary to increase the robustness and reproducibility of biological studies. In this study, the sampling performance of thermal desorption tubes with six common adsorbent material combinations, i.e., Tenax® TA, Tenax® TA/Carbopack™ B, Tenax® TA/Sulficarb, Tenax® TA/Carbograph™ 5TD, Tenax® TA/Carbograph™ 1TD/Carboxen® 1003, and Carboxen® 1013/Carbograph™ 5TD, was evaluated in two different setups: in vitro and in vivo sampling. The in vitro setup consisted of the headspace dynamic extraction of spiked serum, and a mixture of 19 standards was evaluated in terms of response and reproducibility. The in vivo setup consisted into two parts: the first one was based the evaluation of the standard mixture, which was flash-vaporised into Tedlar® bags containing exhaled breath; the second part was based on the longitudinal monitoring of breath metabolites originating from a beverage intake (i.e., brewed coffee), over a 90 min time period. The tubes were all desorbed and analysed in a comprehensive two-dimensional gas chromatography system coupled to a high-resolution time-of-flight mass spectrometer (GC×GC-HR ToF MS). In both sampling setups, the widest analytes coverage and the overall best extraction yield on the selected compounds were obtained using Tenax® TA, followed by Tenax® TA/Carbopack™ B. Tenax® TA provided the highest sampling reproducibility with 12 %RSD, 10 %RSD and < 5 %RSD of the response during the experiments using the in vitro setup, the in vivo setup, and during the longitudinal tracking, respectively. [less ▲]

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See detailUnraveling the Complex Olefin Isomer Mixture Using Two-Dimensional Gas Chromatography-Photoionization-Time of Flight Mass Spectrometry
Zou, Yun ULiege; Stefanuto, Pierre-Hugues ULiege; Maimone, Mariarosa et al

in Journal of Chromatography. A (2021), 1645

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See detail30th Anniversary of comprehensive two-dimensional gas chromatography: Latest advances
Zanella, Delphine ULiege; Focant, Jean-François ULiege; Franchina, Flavio ULiege

in Analytical Science Advances (2021), (2), 213-224

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See detailAdvanced chemometric and data handling tools for GCxGC-TOF-MS
Stefanuto, Pierre-Hugues ULiege; Smolinska, Agnieszka; Focant, Jean-François ULiege

in TrAC: Trends in Analytical Chemistry (2021)

Comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GC GC-MS) hasbecome a mature technique. GC GC-MS can now be used to conduct large scale studies, giving fullaccess to its ... [more ▼]

Comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GC GC-MS) hasbecome a mature technique. GC GC-MS can now be used to conduct large scale studies, giving fullaccess to its high-resolution power for targeted and mostly untargeted screening. The current challengesare now localized on the data management side, where powerful chemometric tools are required tounlock GC GC-MS full potential.This manuscript reviews and discusses recent advances in the development of specific chemometricsfor GC GC-MS. It is designed as a guide to users who desire to establish robust and reproducible GC GC-MS data processing workflows. Each of the critical steps of data preprocessing, feature selection, modelbuilding, and validation are described and considered in detail. Finally, some future perspectives on thedevelopment of the next generation of chemometric tools based on Artificial Intelligence, especiallymachine learning, are critically discussed. [less ▲]

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See detailAdvanced mono‐ and multi‐dimensional gas chromatography–mass spectrometry techniques for oxygen‐containing compound characterization in biomass and biofuel samples
Beccaria, Marco ULiege; Anna Luiza, Mendes Siqueira; Adrien, Maniquet et al

in Journal of Separation Science (2021), 44

A wide variety of biomass, from triglycerides to lignocellulosic‐based feedstock, are among promising candidates to possibly fulfill requirements as a substitute for crude oils as primary sources of ... [more ▼]

A wide variety of biomass, from triglycerides to lignocellulosic‐based feedstock, are among promising candidates to possibly fulfill requirements as a substitute for crude oils as primary sources of chemical energy feedstock. During the feedstock processing carried out to increase the H:C ratio of the products, heteroatom‐containing compounds can promote corrosions, thus limiting and/or deactivating catalytic processes needed to transform the biomass into fuel. The use of advanced gas chromatography techniques, in particular multi‐dimensional gas chromatography, both heart‐cutting and comprehensive coupled to mass spectrometry, has been widely exploited in the field of petroleomics over the past 30 years and has also been successfully applied to the characterization of volatile and semi‐volatile compounds during the processing of biomass feedstock. This review intends to describe advanced gas chromatography–mass spectrometry‐based techniques, mainly focusing in the period 2011–early 2020. Particular emphasis has been devoted to the multi‐dimensional gas chromatography–mass spectrometry techniques, for the isolation and characterization of the oxygen‐containing compounds in biomass feedstock. Within this context, the most recent advances to sample preparation, derivatization, as well as gas chromatography instrumentation, mass spectrometry ionization, identification, and data handling in the biomass industry, are described. [less ▲]

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See detailGC×GC-HRTOFMS for untargeted screening of exhaled breath
Stefanuto, Pierre-Hugues ULiege; Zanella, Delphine ULiege; Franchina, Flavio ULiege et al

Conference (2020, November)

In the galaxy of Omics Science, breathomics (i.e., exhaled breath analysis) knows an exponential growth. The full characterization of the breath composition and the understanding of the origin of these ... [more ▼]

In the galaxy of Omics Science, breathomics (i.e., exhaled breath analysis) knows an exponential growth. The full characterization of the breath composition and the understanding of the origin of these chemicals could have a gigantic impact for clinical research. Indeed, the potential of using non-invasive breath testing for patient status evaluation could be a game changer in disease monitoring and personalized medicine. Following that goal, there are numerous applications under development from cancer detection to diet adjustment. However, the complete characterization of the exhaled breath composition represents a complex analytical quest. From the exhaustive and reliable sampling, through robust untargeted analysis, to validated markers identification, the playground is large and require the development of new analytical workflows. To ensure the robustness of the entire process, every step must be carefully optimized and controlled with a robust QA/QC system. In order to resolve the complex composition of such samples, a powerful analytical technique is required. To obtain an untargeted screening of exhaled breath sample comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GC×GC-MS) is a go to analytical solution. GC×GC-MS provides high separation resolution and orthogonal compounds identification metrics. Indeed, the retention times combined to the MS fragmentogram and potentially to the high-resolution MS provide strong identification confidence, which can reach level 2 MSI (metabolomics standard initiative) classification in a single analysis. The organic and biological analytical chemistry group (OBiAChem) from Liège University has been dedicating a lot of effort to tackle the challenges on the road of robust breath test. In this webinar, we will cover the different technological aspects of exhaled breath research including sampling, analysis, data processing, and QA/QC. In addition, we will cover some clinical applications and discuss the transferability of breath testing for large scale population screening. [less ▲]

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See detailTranslating breath-based asthma phenotyping into clinical practice
Stefanuto, Pierre-Hugues ULiege; Zanella, Delphine ULiege; SCHLEICH, FLorence ULiege et al

Conference (2020, November)

According to the world health organization, asthma and COPD represent the most common chronic respiratory diseases, with respectively 235 and 65 million of people concerned worldwide. These diseases are ... [more ▼]

According to the world health organization, asthma and COPD represent the most common chronic respiratory diseases, with respectively 235 and 65 million of people concerned worldwide. These diseases are not curable. Nevertheless, various forms of treatment that help to dilate major air passages and improve shortness of breath can help to increase the quality of life for patients. However, disease phenotyping relies on invasive sputum analysis. In addition, neutrophilic and eosinophilic inflammation phenotypes have similar symptoms but requires different treatment approaches. To improve monitoring of patients, they have to be better phenotyped. It would allow quick adjustment of the treatment. In this context, we have been developing a breath-based phenotyping approach using thermal desorption and two-dimensional gas chromatography coupled to high resolution mass spectrometry (TD-GC×GC-HRTOFMS). This method allows patient phenotyping with similar performances than the routine clinical practice (Accuracy 72%, AUROC 0.72). Moreover, the combination of breath with other methods, such as FeNO and blood cell count, significantly increases the model performance (Accuracy 76%, AUROC 87%). Our current efforts are focused on facilitating the translation of the method to the clinic and to better understand the origin of the markers used for the classification. To facilitate such translation, we have been working on direct mass spectrometry approach using full scan SIFT-MS. This method allows to phenotype patients with an accuracy around 75 % in less than 3 min. This work is included in the continuous effort around breath research to develop clinical implementation. [less ▲]

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See detailRecent Medical Applications of GCxGC-TOFMS
Stefanuto, Pierre-Hugues ULiege; Focant, Jean-François ULiege

Conference (2020, September)

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See detailThe Ultimate Untargeted Technique
Stefanuto, Pierre-Hugues ULiege; Zanella, Delphine ULiege; Focant, Jean-François ULiege

in The Analytical Scientist (2020), 90

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See detailSpecificity of metabolic colorectal cancer biomarkers in serum through effect size
Di Giovanni, Nicolas ULiege; MEUWIS, Marie-Alice ULiege; LOUIS, Edouard ULiege et al

in Metabolomics (2020), 16(8),

Introduction: Colorectal cancer is one of the most diagnosed cancers, leading to numerous deaths. In addition to existing screening methods, metabolic profiling could help both to diagnose and to ... [more ▼]

Introduction: Colorectal cancer is one of the most diagnosed cancers, leading to numerous deaths. In addition to existing screening methods, metabolic profiling could help both to diagnose and to understand the various states of the disease. Objectives: Find specific candidate biomarkers (CB) in serum of patients with colorectal cancer (CRC), in comparison to the situation after remission (R-CRC), evaluated on distinct patients. Methods: All serum samples were analyzed using comprehensive two-dimensional gas chromatography (GC × GC) coupled to high resolution time of flight mass spectrometry (TOF-MS) through an optimized and validated untargeted analytical method regulated by a quality control (QC) system. First, we used a specific multi-approaches data (pre)processing workflow to highlight, annotate and assess the performances of the most altered metabolites between CRC patients (n = 18) and healthy control samples (HC, n = 19) specifically matched for age and gender, two of the most influential confounding factors. On the contrary, due to the difficulty to control for all clinical and demographic traits when sampling small cohorts, the samples from patients in remission (n = 17) were not matched. Because of the consequent risk of bias, the usual null hypothesis significance tests (NHST) could not be applied reliably. Therefore, we compared the R-CRC samples to another specifically matched group of healthy controls (R-HC, n = 17), and used this comparison to indirectly address the difference between patients with colorectal cancer and patients in remission through a measure called effect size (ES) whose methodological aspects were investigated. Results: 24 candidate biomarkers were found significantly altered and able to discriminate the CRC and HC samples efficiently (Receiver Operating Characteristic (ROC) area under the curve (AUC) of 0.86, sensitivity and specificity of 0.72 and 0.78). 10 of those were found to have signals close to healthy levels in the R-CRC samples and were therefore specific to colorectal cancer. In the point-biserial case studied here, r-like (strength of association) and d-like (standardized mean difference) ES were directly convertible and only linear and rank-based ES were different. We therefore used and recommend Hedges' g, Spearman's rho and Kendall's tau, along with an unstandardized ES. The confidence intervals, that quantify the uncertainty of the measure, were well represented through scatterplots and distribution curves. Conclusion: The candidate biomarkers found, along with their specificity, could help for the detection of colorectal cancer, the diagnosis of remission, and for the understanding of its pathophysiology, after proper validation on independent cohorts. The effect size, here applied on a MS global profiling data set, is an ideal complement to NHST and a useful tool to compare and combine distinct cohorts, within a study as well as between studies (meta-analysis). [less ▲]

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See detailComprehensive Two-dimensional gas-chromatography to study the human exposome: Current trends and perspectives
Weggler, Benedikt ULiege; Gruber, Beate; Focant, Jean-François ULiege

in Current Opinion in Environmental Science and Health (2020), 15

In context of the exposome paradigm, the ‘exposure’ describes all individual and global environmental influences an individual throughout its entire lifetime. Cause, effect and their causality are the ... [more ▼]

In context of the exposome paradigm, the ‘exposure’ describes all individual and global environmental influences an individual throughout its entire lifetime. Cause, effect and their causality are the central research objectives, which require interdisciplinary research strategies. The core benefits of comprehensive two-dimensional gas chromatography (GC×GC) make it a versatile technique for both, exposure and response driven approaches, especially when combined with appropriate sample preparation and MS detection. In this article, the potentials and recent advances of GC×GC in the field of human exposome research is critically discussed. [less ▲]

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See detailMulticlass GC×GC Method for Cannabis Products
Franchina, Flavio ULiege; Dubois, Lena ULiege; Focant, Jean-François ULiege

Conference (2020, June)

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See detailChapter 15: Comprehensive gas chromatography-mass spectrometry
Zanella, Delphine ULiege; Focant, Jean-François ULiege; Hill, Jane et al

in Beauchamp, Jonathan; Davis, Cristina; Pleil, Joachim (Eds.) Breathborne Biomarkers and the Human Volatilome (2020)

The complex chemical composition of exhaled breath presents a real analytical challenge, especially for untargeted screening. Indeed, to ensure appropriate fingerprinting of a sample, high resolving power ... [more ▼]

The complex chemical composition of exhaled breath presents a real analytical challenge, especially for untargeted screening. Indeed, to ensure appropriate fingerprinting of a sample, high resolving power is required. For many years, 1DGC has been the go-to method for volatile mixture characterization. When untargeted resolution of complex samples is required, however, the resolution of the technique reaches its limits. Pushing forward the resolution limitations, GCx GC is the emerging solution. GC xGC relies on the combination of multiple chromatographic dimensions, which can be hyphenated with HRMS. The resulting system allows full sample resolution with a high confidence in compound identification. Nevertheless, such analytical power comes with an increased complexity in method optimization and data handling. For each data point collected, two retention times and a full (HR) mass spectrum is collected at a rate of 100-200 data points per second. So, there is a growing importance in the use of powerful computer tools to assist optimization and high-dimensional data management. The recent efforts to overcome these complications are making GC xGC the method of choice for untargeted volatilomics. In recent years, several successful studies using GC GC have been conducted for different pathologies. In the complex field of cancer research, for example, the use of exhaled breath represents a real hope for large-scale population screenings. Different proof-of-concept and optimization studies have been successfully conducted in cancer research. The resolution power of GC xGC has been compared to classical 1DGC studies in different fields. For asthma characterization, different research projects are pushing the use of GC GC to diagnose and understand lung inflammation. The first large-scale study combining the output of both GC-MS and GCx GC-HRTOFMS has been conducted for discovery and validation of breath volatiles. Moreover, much effort is being devoted to infectious disease detection, with the aim to complement time-consuming culture-based diagnosis. [less ▲]

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See detailInvestigating aroma diversity combining purge‐and‐trap, comprehensive two‐dimensional gas chromatography, and mass spectrometry
Franchina, Flavio ULiege; Zanella, Delphine ULiege; Lazzari, Eliane ULiege et al

in Journal of Separation Science (2020), 43

Headspace gas chromatography is frequently used for aroma profiling thanks to its ability to naturally exploit the volatility of aroma compounds, and also to provide chemical information on sample ... [more ▼]

Headspace gas chromatography is frequently used for aroma profiling thanks to its ability to naturally exploit the volatility of aroma compounds, and also to provide chemical information on sample composition. Its main advantages rely on simplicity, no use of solvent, amenability to automation, and the cleanliness of the extract. In the present contribution, the most effective sampling (dynamic extraction), separation (multidimensional gas chromatography), and detection (mass spectrometry) techniques for untargeted analysis are exploited in combination, showing their potential in unraveling aroma profiles in fruit beers. To complete the overall analytical process, a neat workflow for data analysis is discussed and used for the successful characterization and identification of five different beer flavors (berries, cherry, banana, apple, and peach). From the technical viewpoint, the coupling of purge-andtrap, comprehensive two-dimensional gas chromatography, and mass spectrometry makes the global methodology unique, and it is for the first time discussed. A (low- )flow modulation approach allowed for the full transfer into the second dimension with mass-spectrometry compatible flow (< 7 mL/min), avoiding the need of splitting before detection and making the overall method sensitive (1.2–5.2-fold higher signal to noise ratio compared to unmodulated gas chromatography conditions) and selective. [less ▲]

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