Publications of Gauthier Eppe
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See detailOptimization and validation of HS-SPME-GC-MS for the determination of Furan and Alkylfurans in chocolate-based products: Impact of tempering and laser printing
Alsafra, Zouheir ULiege; Scholl, Georges ULiege; Eppe, Gauthier ULiege

in Journal of AOAC International (in press)

Objectives Two major objectives are presented. Firstly, we aim at optimizing and validating a HS-SPME-GC-MS method for the quantification of 5 alkylfurans in chocolate. Secondly, we focus our study on ... [more ▼]

Objectives Two major objectives are presented. Firstly, we aim at optimizing and validating a HS-SPME-GC-MS method for the quantification of 5 alkylfurans in chocolate. Secondly, we focus our study on measuring the quantitative impact of engraving technique on the formation of furan and its derivatives in chocolate, from the raw callets to processed end-products. Method HS-SPME-GC-MS method operating in SIM mode and using isotope dilution technique with deuterated homologue internal standards was used to quantify alkylfurans in chocolate. Results Good repeatability (RSD% = 0.1-8%, in duplicate) and intermediate precision (RSD% = 1.7-7%, n = 6) were obtained for these five process contaminants at 10, 25, and 50 µg/kg. Trueness was varying between 81 and 109%. LoQ ranged from 0.48 to 2.50 µg/kg. Relative expanded measurement uncertainties ranged from 6 to 30%. Finally, tempering is responsible for a 24% increase in furan contamination, while the laser engraving technique results in an additional 31% increase in furan. A similar trend was also observed for 2-methylfuran and 3-methylfuran, whereas no significant increases were observed for 2,3-dimethylfuran and 2,5-dimethylfuran. Conclusions and highlights A reliable and sensitive method of HS-SPME-GC-MS was reported for the first time for the analysis of furan and four alkylfurans in chocolate. This paper demonstrated that engraving using laser-based techniques can increase the levels of these compounds by up to 30%. [less ▲]

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See detailRadical-Pairing Interactions in a Molecular Switch Evidenced by Ion Mobility Spectrometry and Infrared Ion Spectroscopy
Hanozin, Emeline ULiege; Mignolet, Benoît ULiege; Martens, Jonathan et al

in Angewandte Chemie International Edition (in press)

The digital revolution sets a milestone in the progressive miniaturization of working devices and in the underlying advent of molecular machines. Foldamers involving mechanically entangled components with ... [more ▼]

The digital revolution sets a milestone in the progressive miniaturization of working devices and in the underlying advent of molecular machines. Foldamers involving mechanically entangled components with modular secondary structures are among the most promising designs for molecular switch-based applications. Characterizing the nature and dynamics of their intramolecular network following the application of a stimulus is the key to their performance. Here, we use non-dissociative electron transfers as a reductive stimulus in the gas phase and probe the consecutive co-conformational transitions of a donor-acceptor oligorotaxane foldamer using electrospray mass spectrometry interfaced with ion mobility and infrared ion spectroscopy. The comparison of collision cross section distributions for analogous closed-shell and radical molecular ions sheds light on their respective formation energetics while variations in their respective infrared absorption bands evidence different intramolecular organizations as the foldamer gets compact. These differences are compatible with the advent of radical-pairing interactions. [less ▲]

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See detailMass shift in Mass Spectrometry Imaging: comprehensive analysis and practical corrective workflow
Mc Cann, Andréa ULiege; Rappe, Sophie ULiege; La Rocca, Raphaël ULiege et al

in Analytical and Bioanalytical Chemistry (2021)

tentative identification of compounds based on their m/z value. In typical MSI, a spectrum is taken at incremental 2D coordinates (pixels) across a sample surface. Single pixel mass spectra show the ... [more ▼]

tentative identification of compounds based on their m/z value. In typical MSI, a spectrum is taken at incremental 2D coordinates (pixels) across a sample surface. Single pixel mass spectra show the resolving power of the mass analyzer. Mass shift, i.e., variations of the m/z of the same ion(s), may occur from one pixel to another. The superposition of shifted masses from individual pixels peaks apparently degrades the resolution and the mass accuracy in the average spectrum. This leads to low confidence annotations and biased localization in the image. Besides the intrinsic performances of the analyzer, the sample properties (local composition, thickness, matrix deposition) and the calibration method are sources of mass shift. Here, we report a critical analysis and recommendations to mitigate these sources of mass shift. Mass shift 2D distributions were mapped to illustrate its effect and explore systematically its origin. Adapting the sample preparation, carefully selecting the data acquisition settings, and wisely applying post-processing methods (i.e., m/z realignment or individual m/z recalibration pixel by pixel) are key factors to lower the mass shift and to improve image quality and annotations. A recommended workflow, resulting from a comprehensive analysis, was successfully applied to several complex samples acquired on both MALDI ToF and MALDI FT-ICR instruments. [less ▲]

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See detailDual-polarity SALDI FT-ICR MS imaging and Kendrick mass defect data filtering for lipid analysis
Müller, Wendy ULiege; Verdin, Alexandre ULiege; Kune, Christopher ULiege et al

in Analytical and Bioanalytical Chemistry (2021), 413(10), 28212830

Lipids are biomolecules of crucial importance involved in critical biological functions. Yet, lipid content determination using mass spectrometry is still challenging due to their rich structural ... [more ▼]

Lipids are biomolecules of crucial importance involved in critical biological functions. Yet, lipid content determination using mass spectrometry is still challenging due to their rich structural diversity. Preferential ionisation of the different lipid species in the positive or negative polarity is common, especially when using soft ionisation mass spectrometry techniques. Here, we demonstrate the potency of a dual-polarity approach using surface-assisted laser desorption/ionisation coupled to Fourier transform-ion cyclotron resonance (SALDI FT-ICR) mass spectrometry imaging (MSI) combined with Kendrick mass defect data filtering to (i) identify the lipids detected in both polarities from the same tissue section and (ii) show the complementarity of the dual-polarity data, both regarding the lipid coverage and the spatial distributions of the various lipids. For this purpose, we imaged the same mouse brain section in the positive and negative ionisation modes, on alternate pixels, in a SALDI FT-ICR MS imaging approach using gold nanoparticles (AuNPs) as dual-polarity nanosubstrates. Our study demonstrates, for the first time, the feasibility of (i) a dual-polarity SALDI-MSI approach on the same tissue section, (ii) using AuNPs as nanosubstrates combined with a FT-ICR mass analyser and (iii) the Kendrick mass defect data filtering applied to SALDI-MSI data. In particular, we show the complementarity in the lipids detected both in a given ionisation mode and in the two different ionisation modes. [less ▲]

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See detailUgi four-component polymerization of amino acid derivatives: a combinatorial tool for the design of polypeptoids
Stiernet, Pierre ULiege; Couturaud, Benoit; Bertrand, Virginie ULiege et al

in Polymer Chemistry (2021)

Polypeptoids, consisting in nitrogen-substituted analogues of polypeptides, have become a real asset in modern sciences especially in the biomedical field. To address the increasing demand for polypeptoid ... [more ▼]

Polypeptoids, consisting in nitrogen-substituted analogues of polypeptides, have become a real asset in modern sciences especially in the biomedical field. To address the increasing demand for polypeptoid structures with specific properties, this work explores the combinatorial character of the Ugi-four component polymerization of amino acid derivatives such as dipeptides and aminobutyric acid compounds, with different aldehydes and isocyanides. A library of structurally diverse polypeptoids is prepared accordingly. Thermal and solution properties of the latter are characterized and discussed in a structure-property relationship approach highlighting the impact of both the backbone and side chains. Some materials demonstrate pH-responsiveness, thermo-responsiveness with tunable transition temperatures and biocompatibility. Given the great variety of possible substrates and the promising properties of the obtained polypeptoids, this straightforward and combinatorial strategy is attractive for the future development of polypeptoids and resulting applications. [less ▲]

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See detailAdaptive Pixel Mass Recalibration for Mass Spectrometry Imaging Based on Locally Endogenous Biological Signals.
La Rocca, Raphaël ULiege; Kune, Christopher ULiege; Tiquet, Mathieu ULiege et al

in Analytical Chemistry (2021)

Mass spectrometry imaging (MSI) is a powerful and convenient method for revealing the spatial chemical composition of different biological samples. Molecular annotation of the detected signals is only ... [more ▼]

Mass spectrometry imaging (MSI) is a powerful and convenient method for revealing the spatial chemical composition of different biological samples. Molecular annotation of the detected signals is only possible if a high mass accuracy is maintained over the entire image and the m/z range. However, the change in the number of ions from pixel-to-pixel of the biological samples could lead to small fluctuations in the detected m/z-values, called mass shift. The use of internal calibration is known to offer the best solution to avoid, or at least to reduce, mass shifts. Their “a priori” selection for a global MSI acquisition is prone to false positive detection and therefore to poor recalibration. To fill this gap, this work describes an algorithm that recalibrates each spectrum individually by estimating its mass shift with the help of a list of pixel-specific internal calibrating ions, automatically generated in a data-adaptive manner (https://github.com/LaRoccaRaphael/MSI_recalibration). Through a practical example, we applied the methodology to a zebrafish whole-body section acquired at a high mass resolution to demonstrate the impact of mass shift on data analysis and the capability of our algorithm to recalibrate MSI data. In addition, we illustrate the broad applicability of the method by recalibrating 31 different public MSI data sets from METASPACE from various samples and types of MSI and show that our recalibration significantly increases the numbers of METASPACE annotations (gaining from 20 up to 400 additional annotations), particularly the high-confidence annotations with a low false discovery rate. [less ▲]

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See detailAnthropogenic particles in sediment from an Arctic fjord
Collard, France; Husum, Katrine; Eppe, Gauthier ULiege et al

in Science of the Total Environment (2021)

The research on plastic pollution is increasing worldwide but little is known about the contamination levels in the Arctic by microplastics and other anthropogenic particles (APs) such as dyed !bres. In ... [more ▼]

The research on plastic pollution is increasing worldwide but little is known about the contamination levels in the Arctic by microplastics and other anthropogenic particles (APs) such as dyed !bres. In this study, two different sampling designs were developed to collect 68 sediment subsamples in !ve locations in a remote Arctic fjord, Kongsfjorden, northwest of Svalbard. Those !ve stations composed a transect from a sewage outlet recently installed close to the northernmost settlement, Ny-Ålesund, to an offshore site. Plastics and other APs were ex- tracted by density separation and analysed by both Raman and Fourier Transform Infrared spectroscopy. Among the 37 APs found, 19 were microplastics. The others were classi!ed as APs due to the presence of a dye or another additive. On average, 0.33 AP 100 g!1 were found in the surface sediment and their sizes ranged between 0.10 and 6.31 mm. The site most polluted by APs was located at the mouth of the fjord while the less polluted ones were the offshore and the outlet sites. We believe that currents in the fjord have carried APs towards the mouth of the fjord where an eddy could retain APs which might sink the sea"oor due to various reasons (ingestion & packag- ing, fouling-induced changes in buoyancy). In the cores, several different APs were found down to a depth of 12 cm. These APs may have been present in the sediments for decades or been transported deeper by biota. Here we pro- vided data on plastic but also on other anthropogenic particles from a remote fjord in Svalbard. [less ▲]

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See detailUV-screening pigment enabling ancient photosynthesis
Lara, Yannick ULiege; Mc Cann, Andréa ULiege; Malherbe, Cédric ULiege et al

Conference (2021)

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See detailSurface‐assisted laser desorption/ionization mass spectrometry imaging: A review
Müller, Wendy ULiege; Verdin, Alexandre ULiege; De Pauw, Edwin ULiege et al

in Mass Spectrometry Reviews (2020)

In the last decades, surface‐assisted laser desorption/ionization mass spectrometry (SALDI‐MS) has attracted increasing interest due to its unique capabilities, achievable through the nanostructured ... [more ▼]

In the last decades, surface‐assisted laser desorption/ionization mass spectrometry (SALDI‐MS) has attracted increasing interest due to its unique capabilities, achievable through the nanostructured substrates used to promote the analyte desorption/ionization. While the most widely recognized asset of SALDI‐MS is the untargeted analysis of small molecules, this technique also offers the possibility of targeted approaches. In particular, the implementation of SALDI‐MS imaging (SALDI‐MSI), which is the focus of this review, opens up new opportunities. After a brief discussion of the nomenclature and the fundamental mechanisms associated with this technique, which are still highly controversial, the analytical strategies to perform SALDI‐MSI are extensively discussed. Emphasis is placed on the sample preparation but also on the selection of the nanosubstrate (in terms of chemical composition and morphology) as well as its functionalization possibilities for the selective analysis of specific compounds in targeted approaches. Subsequently, some selected applications of SALDI‐MSI in various fields (i.e., biomedical, biological, environmental, and forensic) are presented. The strengths and the remaining limitations of SALDI‐MSI are finally summarized in the conclusion and some perspectives of this technique, which has a bright future, are proposed in this section. [less ▲]

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See detailMultiplex micro-SERS imaging of cancer-related markers in cells and tissues using poly(allylamine)-coated Au@Ag nanoprobes
Verdin, Alexandre ULiege; Malherbe, Cédric ULiege; Müller, Wendy ULiege et al

in Analytical and Bioanalytical Chemistry (2020), 412(25),

Surface-enhanced Raman scattering (SERS) nanoprobes based on Au@Ag core@shell nanoparticles coated with poly(allylamine) were functionalized with small targeting molecules to evaluate simultaneously the ... [more ▼]

Surface-enhanced Raman scattering (SERS) nanoprobes based on Au@Ag core@shell nanoparticles coated with poly(allylamine) were functionalized with small targeting molecules to evaluate simultaneously the level of expression of two cancer-related markers, both in cells and in tissues. The Au@Ag nanoparticles provide a high SERS signal enhancement in the visible range when combined with resonant Raman-active molecules. The poly(allylamine) coating plays a dual key role in (i) protecting the metal surface against the complex biological medium, leading to a stable signal of the Raman-active molecules, and (ii) enabling specific biofunctionalization through its amine functions. Using small targeting molecules linked to the polymer coating, two different nanoprobes (duplex approach) were designed. Each was able to specifically target a particular cancer-related marker: folate receptors (FRs) and sialic acid (SA). We demonstrate that the level of expression of these targeted markers can be evaluated following the SERS signal of the probes incubated on cells or tissues. The potential overexpression of folate receptors and of sialic acid was evaluated and measured in breast and ovarian cancerous tissue sections. In addition, FR and/or SA overexpression in the tumor region can be visualized with high contrast with respect to the healthy region and with high spatial accuracy consistent with histology by SERS imaging of the nanoprobe signal. Owing to the unique spectral signature of the designed nanoprobes, this approach offers an efficient tool for the spatially resolved, in situ measurement of the expression level of several cancer-related markers in tumors at the same time. [less ▲]

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See detailUnravelling chemical mechanisms in microbial interactions by combining thin layer chromatography, ion mobility and MALDI imaging mass spectrometry
Mc Cann, Andréa ULiege; Kune, Christopher ULiege; La Rocca, Raphaël ULiege et al

Conference (2020, June 01)

Mass spectrometry (MS) is a method of choice in microbiology for untargeted detection and identification of bioactive compounds. Mass Spectrometry Imaging (MSI) has led to a growing interest in the in ... [more ▼]

Mass spectrometry (MS) is a method of choice in microbiology for untargeted detection and identification of bioactive compounds. Mass Spectrometry Imaging (MSI) has led to a growing interest in the in situ study of biomolecules produced when microorganisms interact with each other. However, in situ identification is still time-consuming and challenging due to the large chemical diversity contained in each pixel of the samples, resulting in very complex average MS spectra. Here, we propose to exploit the power of combining Kendrick Mass Defect (KMD) analysis and collision cross section (CCS) values using mobility for the characterization of families of related compounds in MSI. The identification of compounds was supported by rapid thin layer chromatography (TLC) separation coupled to MALDI-MS/MS detection. Bacillus velezensis GA1 and Pseudomonas sp. CMR12a were inoculated at different distances (0.5, 1 and 2 cm) on a semi-solid agar-based medium and incubated at 30°C. Regions of interest were cut directly from the Petri dish and transferred to the target ITO plate. This assembly was placed in a vacuum desiccator until completely dry and covered with HCCA matrix (Sunchrom sprayer). Ion mobility in imaging mode was performed using the timsTOF fleX (Bruker Daltonics, Bremen, Germany). TLC separation of ROI extracts is analyzed by MALDI-MS/MS imaging on the rapifleX instrument (Bruker Daltonics) for rapid screening of compounds and on the solariX instrument (Bruker Daltonics) for exact mass and isotopic distribution. The data were processed and integrated with in-house software. The coupling of MALDI-MSI with ion mobility separation brings additional structural features/information. It allows data to be filtered according to a range of CCS values and it improves the confidence level for the identification of detected analytes, in addition to exact mass determination. A relationship between CCS and mass was also performed. In combination with KMD analysis, various families of compounds, such as lipids or lipopeptides could be automatically detected and identified. Through this workflow, the comparison of the three different culture conditions was greatly simplified and highlighted the changes that occur in the metabolism of the bacteria. In particular, we were able to observe a variation within the lipid composition of Pseudomonas sp. CMR12a as a function of distance from the Bacillus velezensis GA1 colony. Finally, TLC separation was successfully optimized for lipopeptides and lipids and validated the identification of detected compounds by simplifying the spectra and allowing image analysis. TLC also enables high throughput, in part due to the parallel imaging of up to 6 traces on a single TLC run. TLC plate matrix coating strategies were compared to optimize the MALDI MS signal. This workflow will also be applied to time-lapse (or time-dependent) experiments, to monitor the bioactive compounds production and migration as a function of the co-culture interaction time. [less ▲]

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See detailSolvent Adducts in Ion Mobility Spectrometry: Toward an Alternative Reaction Probe for Thermometer Ions
Morsa, Denis ULiege; Hanozin, Emeline ULiege; Eppe, Gauthier ULiege et al

in Journal of the American Society for Mass Spectrometry (2020)

The fragmentation of benzylpyridinium "thermometer" ions is widely used to quantify the energetics of ions studied by mass spectrometry and other hyphenated techniques such as ion mobility. The reaction ... [more ▼]

The fragmentation of benzylpyridinium "thermometer" ions is widely used to quantify the energetics of ions studied by mass spectrometry and other hyphenated techniques such as ion mobility. The reaction pathway leads to a benzylium cation with the release of a neutral pyridine. Using trapped ion mobility spectrometry, we noticed that the addition of acetonitrile, present in the electrosprayed solvent mixture, could occur on some electrophilic benzylium cations. This process results in the formation of adducts and in the appearance of a supplementary mobility peak. We here demonstrate that the addition takes place both in the electrospray source and inside the mobility analyzer, thereby evidencing possible outflow of solvent vapors downstream the instrument. By further characterizing the initial kinetics and the resulting equilibrium linked with the addition reaction, we presently discuss these as alternative probes to calibrate ion temperature in the framework of ion mobility. [less ▲]

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See detailHuman Liver-Derived Extracellular Matrix for the Culture of Distinct Human Primary Liver Cells
Alevra Sarika, Niki; Payen, Valéry; Fleron, Maximilien ULiege et al

in Cells (2020), 9(6)

The lack of robust methods to preserve, purify and in vitro maintain the phenotype of the human liver’s highly specialized parenchymal and non-parenchymal cell types importantly hampers their exploitation ... [more ▼]

The lack of robust methods to preserve, purify and in vitro maintain the phenotype of the human liver’s highly specialized parenchymal and non-parenchymal cell types importantly hampers their exploitation for the development of research and clinical applications. There is in this regard a growing interest in the use of tissue-specific extracellular matrix (ECM) to provide cells with an in vitro environment that more closely resembles that of the native tissue. In the present study, we have developed a method that allows for the isolation and downstream application of the human liver’s main cell types from cryopreserved material. We also isolated and solubilized human liver ECM (HL-ECM), analyzed its peptidomic and proteomic composition by mass spectrometry and evaluated its interest for the culture of distinct primary human liver cells. Our analysis of the HL-ECM revealed proteomic diversity, type 1 collagen abundance and partial loss of integrity following solubilization. Solubilized HL-ECM was evaluated either as a coating or as a medium supplement for the culture of human primary hepatocytes, hepatic stellate cells and liver sinusoidal endothelial cells. Whereas the solubilized HL-ECM was suitable for cell culture, its impact on the phenotype and/or functionality of the human liver cells was limited. Our study provides a first detailed characterization of solubilized HL-ECM and a first report of its influence on the culture of distinct human primary liver cells. [less ▲]

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See detailMicrostructural and compositional variation in pacu and piranha teeth related to diet specialization (Teleostei: Serrasalmidae)
Delaunois, Yann ULiege; Huby, Alessia ULiege; Malherbe, Cédric ULiege et al

in Journal of Structural Biology (2020), 210

In any vertebrate group, tooth shape is known to fit with a biological function related to diet. However, little is known about the relationships between diet and tooth microstructure and composition in ... [more ▼]

In any vertebrate group, tooth shape is known to fit with a biological function related to diet. However, little is known about the relationships between diet and tooth microstructure and composition in teleost fishes. In this work, we describe the external morphology, internal microstructure and elemental composition of the oral teeth of three representative species of the family Serrasalmidae having different feeding habits (herbivorous vs. omnivorous vs. carnivorous). We used backscattered-electron imaging and low vacuum environmental scanning electron microscope to compare the organization and mineralization of tooth layers as well as energy dispersive X-ray microanalysis and Raman microspectrometry to investigate the elemental composition, Ca/P ratio and mineralogy of the most superficial layers. Oral teeth of each serrasalmid species have the same internal orga- nization based on five distinctive layers (i.e. pulp, dentine, inner enameloid, outer enameloid and cuticle) but the general tooth morphology is different according to diet. Microstructural and compositional variation of the cuticle and iron-enrichment of superficial layers were highlighted between herbivorous and carnivorous species. Iron is more concentrated in teeth of the herbivorous species where it is associated with a thicker cuticle ex- plaining the more intense red-pigmentation of the cutting edges of oral teeth. The iron-enrichment is interpreted as a substitution of Ca by Fe in the hydroxyapatite. These traits are discussed in the light of the evolutionary history of the family. Further considerations and hypotheses about the formation and origin of the mineralized tooth layers and especially the iron-rich superficial layers in teleost fishes are suggested. [less ▲]

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See detailIsolation and Characterization of Two Microalgal Isolates from Vietnam with Potential for Food, Feed, and Biodiesel Production
Luu Thao Nguyen, ULiege; Alsafra, Zouheir ULiege; Corato, Amélie ULiege et al

in Energies (2020), 13

Microalgae are promising feedstock for the production of biodiesel and diverse medium- and high-value products such as pigments and polyunsaturated fatty acids. The importance of strain selection adapted ... [more ▼]

Microalgae are promising feedstock for the production of biodiesel and diverse medium- and high-value products such as pigments and polyunsaturated fatty acids. The importance of strain selection adapted to specific environments is important for economical purposes. We characterize here two microalgal strains, isolated from wastewater of shrimp cultivation ponds in Vietnam. Based on the 18S rDNA-ITS region, one strain belongs to the Eustigmatophyceae class and is identical to the Nannochloropsis salina isolate D12 (JX185299.1), while the other is a Chlorophyceae belonging to the Desmodesmus genus, which possesses a S516 group I intron in its 18S rDNA gene. The N. salina strain is a marine and oleaginous microalga (40% of dry weight (DW) at stationary phase) whole oil is rich in saturated fatty acids (around 45% of C16:0) suitable for biodiesel and contains a few percent of eicosapentaenoic acid (C20:5). The Desmodesmus isolate can assimilate acetate and ammonium and is rich in lutein. Its oil contains around 40%–50% α-linolenic acid (C18:3), an essential fatty acid. Since they tolerate various salinities (10% to 35‰), both strains are thus interesting for biodiesel or aquaculture valorization in coastal and tropical climate where water, nutrient, and salinity availability vary greatly depending on the season. [less ▲]

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See detailIn-line monitoring of glyphosate in a microfluidic setup by SERS, development and optimization by DoE
Emonds-Alt, Gauthier ULiege; Avohou, Tonakpon Hermane ULiege; Kasemiire, Alice ULiege et al

Poster (2020, January 28)

Quantifying and monitoring trace amounts of glyphosate and pesticide residues in the environment typically relies on analytical methods such as Gas Chromatography (GC) or Liquid Chromatography (LC ... [more ▼]

Quantifying and monitoring trace amounts of glyphosate and pesticide residues in the environment typically relies on analytical methods such as Gas Chromatography (GC) or Liquid Chromatography (LC) coupled with mass spectrometry (MS) [4]. However, these types of methods are expensive and often less suitable for in situ field analysis. Surface Enhanced Raman Spectroscopy (SERS) coupled with microfluidic could be an alternative method, which allows a fast and direct quantification on the field [5] with miniaturised instrumentation. Indeed, SERS combines the advantage of Raman spectroscopy and is able to detect traces due to the signal enhancement resulting from the adsorption of the analyte on the rough nanoparticle surface [6]. [less ▲]

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See detailData processing and interpretation of mass spectrometry imaging using high resolving mass power
Mc Cann, Andréa ULiege; La Rocca, Raphaël ULiege; Kune, Christopher ULiege et al

Poster (2020, January 28)

1 Introduction Mass Spectrometry Imaging (MSI) is a powerful analytical tool allowing untargeted investigation of spatial distribution of molecular species in a large variety of samples, by recording 2D ... [more ▼]

1 Introduction Mass Spectrometry Imaging (MSI) is a powerful analytical tool allowing untargeted investigation of spatial distribution of molecular species in a large variety of samples, by recording 2D distribution of all the detectable compounds in the sample. Over the years, the application of MSI has become increasingly diverse, from bacteria-bacteria interaction understanding to biomarker discovery. To this end, it is necessary to combine high spectral resolution with efficient data processing, in order to maximise the extraction of the information contained in large datasets. Moreover, in addition to deal with thousands of features, pixel-to-pixel mass shift must be taken into account before applying any data-mining tool. For that reason, we propose the combination of a post-acquisition label-free recalibration method and an algorithm to cluster features based on their Kendrick mass defect (KMD) in MSI. 2 Theory KMD consists in a change of basis from the IUPAC mass scale to a Kendrick mass based on the nominal mass of a defined Kendrick mass unit, such as CH2 (here, nominal mass is set at 14 a.u.)1. The KMD is obtained by subtracting the nominal Kendrick mass to the exact Kendrick mass. This mathematical transformation enables to map the detected molecules in mass spectrometry based on their chemical composition. 3 Material and methods MALDIFT-ICR-MS (SolariX XR 9.4T) images were first converted into imzML open format. Each spectrum from the imzML file obtained for an MSI are individually peak picked. Then, our algorithm creates, for each pixel, a linear model linking m/z error and m/z. The model is creating by finding database hit with similar mass shift. Finally, a new imzML file is created by recalibrating each pixel with their estimated linear model. Then, we developed a software to filter features (m/z peaks) based on their KMD from an imzML file. This software calculates first a KMD for each m/z values detected in the mean mass spectrum of the image. The MSI data is then filtered based on KMD value to conserve only ions whose KMD is included in the user-defined KMD range. The reduced ion lists were then divided into different compounds families, based on the repetition of the KMD. Finally, an image is generated for each compounds family. Thereby reducing the number of features of an image2. 4 Results and discussion The KMD filtering method applied on a mouse brain tissue analysis by MSI appears to be biologically relevant since it enabled to map in a single step all members of important families of biomolecules. Among the detected families of biomolecules, lipids shows different distributions and localisations. Some of these lipids belonged to the glycerophosphocholines (GPCs), the hexosylceramides (HexCers), lysophoshocholins (LPCs) and the sphingomyelins (SMs) class. Moreover, The KMD analysis highlighted that some of the detected GPCs on the brain tissue sections from mouse were differentially co-localized, depending on their unsaturation degree. All these results suggested that the KMD could be considered instead of the mass-to-charge (m/z) values classically used for the analysis of images by MSI. The use of our in-house developed software for KMD analysis enables an automated, faster and efficient data analysis of MSI images. 5 Conclusion The combination of recalibration before using Kendrick mass defect mass filter is an essential step to be able to interpret the image reconstruction of chemically-related compounds. This methods speed up the identification process and facilitates the data analysis without losing data information. [less ▲]

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See detailDiscrimination of textile dyes in binary mixtures by Raman spectroscopy
Lepot, Laurent ULiege; De Wael, Kris; Gason, Fabrice et al

in Journal of Raman Spectroscopy (2020)

For forensic investigation of dyes used in the textile dying industry by Raman spectroscopy, the capability to discriminate several dyes is signifi- cant. When trace samples of fibres tainted with unknown ... [more ▼]

For forensic investigation of dyes used in the textile dying industry by Raman spectroscopy, the capability to discriminate several dyes is signifi- cant. When trace samples of fibres tainted with unknown dyes have to be confronted to a reference material, the minor dye is typically present in less than 10 wt% in the dyeing preparations. In the present study, we investigate the ability of Raman spectroscopy to discriminate two dyes in binary mixtures. 50 mixtures were prepared from a selection of five textile dyes in various molar proportion. They were systematically studied with two excitation laser sources at 514 nm and at 785 nm, both referenced in the forensic fibre literature. Representative data were obtained for different scenario's considering the relative capability of each dye to lead to high or weak Raman signal as well as possible fluorescence emission. In particular, we discuss the complementarity of the data obtained with both lasers and the supervised data exploratory treatments leading to the detection of the dye signal: from the simple observation by the operator, the search in spec- tral databases to the quantitative spectral subtraction of the dominant dye contribution. [less ▲]

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See detailRemoval of phosphate from wastewater using coal slag
Nguyen, Lam; Hoa, Thai Ma; Bashir, Mohammed et al

in International Journal of Environmental Analytical Chemistry (2020)

Adsorption is an efficient, cost-effective, and eco-friendly method for the treatment of phosphorus from wastewater. This work presents the adsorptive removal of phosphate ions in aqueous solution using ... [more ▼]

Adsorption is an efficient, cost-effective, and eco-friendly method for the treatment of phosphorus from wastewater. This work presents the adsorptive removal of phosphate ions in aqueous solution using coal slag (CS) from a thermal power plan. The surface morphological analysis showed that the CS particles were around 50 µm with a surface area of 9.20 m2 g−1 and adsorption average pore width of 6.42 nm, offering the high capability for phosphate ions adsorption. The optimising phosphate ions adsorption conditions were investigated based on various parameters, including contact time, pH, and amount of absorbent. The experimental results showed that the maximum loading adsorption capacity was 21.63 mg g−1 in the concentration range of 0–30 mg L−1 under optimising conditions (i.e. pH of 6, adsorbent dosage (0.1 g vol−1 used) and contact time of 45 min). Furthermore, the use of CS offers several benefits like reducing the sample pre-treatment steps for costly, less time-consuming and reliable methods. [less ▲]

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See detailEffective Temperature and Structural Rearrangement in Trapped Ion Mobility Spectrometry
Morsa, Denis ULiege; Hanozin, Emeline ULiege; Eppe, Gauthier ULiege et al

in Analytical Chemistry (2020)

Modern ion mobility instrumentations are typically operated above the low field limit, which may activate the ions and cause structural rearrangement or fragmentation during the analysis. Here, we ... [more ▼]

Modern ion mobility instrumentations are typically operated above the low field limit, which may activate the ions and cause structural rearrangement or fragmentation during the analysis. Here, we quantitatively assessed the internal heating experienced by ions during trapped ion mobility spectrometry (TIMS) experiments. To this end, the fragmentation yields of fragile benzylpyridinium “thermometer” ions were monitored during both the accumulation and analysis steps inside the TIMS tunnel. The corresponding fragmentation rate constants were translated into a vibrational effective temperature Teff,vib. Our results demonstrate significant fragmentation upstream and inside the TIMS tunnel that corresponds to Teff,vib ≈ 510 K during both the accumulation and analysis steps. Broadening our scope to cytochrome c and lysozyme, we showed that although compact “native” folds can be preserved, the collision cross section distributions are highly sensitive to the transmission voltages and the analysis timescale. Our results are discussed with regard to Teff,vib data previously acquired on traveling-wave (TWIMS) ion mobility in the context of native mass spectrometry and conformational landscape exploration. [less ▲]

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