References of "Focant, Jean-François"
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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 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 (2020)

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 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 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 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 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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See detailMultimodal Approaches for Untargeted Screening for Medical Applications of the Human Volatilome
Stefanuto, Pierre-Hugues ULiege; Zanella, Delphine ULiege; SCHLEICH, FLorence ULiege et al

Conference (2020, March)

The ballistic rise of analytical technologies has opened a large playground for all type of untargeted “omics” screening. In that trend, there is a rising interest for the characterization of the human ... [more ▼]

The ballistic rise of analytical technologies has opened a large playground for all type of untargeted “omics” screening. In that trend, there is a rising interest for the characterization of the human volatilome. Indeed, the characterization and the understanding of the volatile organic compounds (VOCs) production in different ex vivo matrices could open the route for improved diagnosis approach and new treatment. In the field of volatilomics, separation science based on multidimensional methods such as comprehensive two-dimensional gas chromatography (GC×GC) appeared as one of the methods of choice for the characterization complex VOC mixtures. At the price of high cost equipment and limited adaptability to routine medical usage, GC×GC offers the possibility to almost completely characterize a sample. For large scale screening, direct introduction instruments such as selected ion flow tube mass spectrometry (SIFT-MS) offered the capacity to perform both targeted and untargeted analyses within a few minutes. SIFT-MS can generate compositional patterns from direct sample introduction at the same time than other routine medical actions. These two orthogonal approaches for pathology screening should ideally conduct to identical sample classifications but have never been directly compared over an identical set of patients. In order to evaluate their complementarity, breath from 50 well-characterized asthmatic patients were analyzed by both approaches. Breath samples were collected using Tedlar bags. For GC×GC-HRTOFMS analyses, the bags were transferred onto thermal desorption tubes prior to injection. For SIFT-MS, the bags were directly emptied into the instrument. Next, data were analyzed using identical processing workflow. We observed that both approaches offered similar classification capacities. GC×GC-HRTOFMS allowed identifying the putative markers for comparison with previous studies and metabolic interpretation, while SIFT-MS offered a faster screening capacity. [less ▲]

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See detailEstablishing a Unique Open-Source Benchmark Dataset for the Comprehensive Evaluation of GC×GC Software
Weggler, Benedikt ULiege; Dubois, Lena ULiege; Zoccali, Mariosimone et al

Conference (2020, January 30)

Two-dimensional gas chromatography is amongst the most powerful separation technologies currently available. Since its advent in 1990, it has become an established method which is readily available ... [more ▼]

Two-dimensional gas chromatography is amongst the most powerful separation technologies currently available. Since its advent in 1990, it has become an established method which is readily available. However, one of its most challenging aspects, especially in hyphenation with mass spectrometry, is the high amount of chemical information it provides for each measurement. The GC×GC community agrees that there the highest demand for action [1–3]. In response, the number of software packages allowing for in-depth data analysis of GC×GC data has risen over the last couple of years. These packages provide sophisticated tools and algorithms allowing for more streamlined data evaluation. However, the tools/algorithms and their functionality differ drastically within the available software packages. This study focuses on two main objectives: first, establishing an open-source dataset for benchmarking, and second, streamlined evaluation guidelines for comprehensive comparison for GC×GC software. Thereby, the benchmark data includes, a set of standard compound measurements and a set of chocolate aroma profiles. On this foundation, eight readily available GC×GC software packages were investigated for fundamental and advanced functionality. [less ▲]

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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 (2020, January 22)

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See detailThe use of GCxGC for forensic applications
Dubois, Lena ULiege; Focant, Jean-François ULiege

Scientific conference (2020, January 16)

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See detailMoving out of the classroom for a comprehensive evaluation of GC×GC Software
Dubois, Lena ULiege; Bhatt, Kinjal ULiege; Franchina, Flavio ULiege et al

Conference (2020, January 08)

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See detailIn vitro characterization of lung inflammation mechanisms
Focant, Jean-François ULiege; Zanella, Delphine ULiege; HENKET, Monique ULiege et al

Conference (2020, January)

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See detailOptimization of a multidimensional gas chromatographic separation. Classical steps toward a better characterization of the separation space.
Gaida, Meriem ULiege; Bhatt, Kinjal ULiege; Franchina, Flavio ULiege et al

Poster (2020, January)

The chromatographic separation in multidimensional gas chromatography is significantly affected by the interactions between the involved experimental parameters[1]. In order to achieve the best separation ... [more ▼]

The chromatographic separation in multidimensional gas chromatography is significantly affected by the interactions between the involved experimental parameters[1]. In order to achieve the best separation possible, these parameters need to be thoroughly optimized. Chromatographic procedures are optimized by varying one parameter at a time, thereby disregarding interactions between the two separation dimensions and resulting in time- consuming procedures[2]. Moreover, the metrics of chromatographic optimization are sometimes not clearly defined or solely based on the user’s expertise and/or intuition. In the present study, chromatographic factors were measured from a designed set of GC×GC- ToF-MS analysis of standards. These factors were used to derive specific outcomes that allowed for a detailed characterization of the two-dimensional (2D) separation space. Furthermore, the result of a design of experiments approach allowed for a statistical investigation of commonly optimized factors, namely flow rate, modulation time, and temperature ramp based on the derived outcomes. Initial findings suggest that differences in chemical groups tend to impact the 2D separation. It also highlights a correlation between the influencing factors and the chemical composition of the studied compounds. Additionally, special attention was paid to the structural similarities between the studied compounds, as well as to wraparound effects and their consequences on the derived outcomes. References: [1] J. Harynuk and T. Górecki, “Experimental variables in GC×GC: A complex interplay,” Am. Lab., vol. 39, no. 4, pp. 36–39, 2007. [2] A. Mostafa, M. Edwards, and T. Górecki, “Optimization aspects of comprehensive two- dimensional gas chromatography,” J. Chromatogr. A, vol. 1255, pp. 38–55, 2012. [less ▲]

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