References of "Far, Johann"
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See detailInnovative analytical strategies for small molecules analysis by ion-mobility mass spectrometry
Eppe, Gauthier ULg; Goscinny, Séverine; Far, Johann ULg et al

Conference (2014, January)

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See detailInnovative analytical strategy using ion-mobility shifting additive for isobaric selenium compound identification in selenomethionine standards by IMS
Kune, Christopher ULg; Far, Johann ULg; Eppe, Gauthier ULg et al

Conference (2013, July 09)

Selenium (Se) is a trace element which is both essential and toxic depending on its concentration and its chemical form. Selenomethionine (SeMet) is one of the widely used selenium standard during ... [more ▼]

Selenium (Se) is a trace element which is both essential and toxic depending on its concentration and its chemical form. Selenomethionine (SeMet) is one of the widely used selenium standard during Selenium speciation studies. This work was focused on the elaboration of an analytical strategy for the detection and the structural elucidation of an isobaric Se interference, which is found in standard solutions of SeMet by high resolution mass spectrometry (Rm/Δm > 20.000). The structural elucidation of these compounds requires the isolation of the respective parent ion. Nevertheless, the mass difference between SeMet and its interference is less than 0.02Da which is well below the window selection of conventional techniques in mass spectrometry (Quadripole, ion trap). The empirical formula and double bound equivalent (DBE) of these ions suggest different tridimensional structures which lead to a discrimination depending on the ion mobility. This separation is observed, both in gaseous and liquid phase, by Ion Mobility Spectrometry (IMS), Capillary Electrophoresis (CE) and Liquid Chromatography (LC) which are hyphenated to mass spectrometry as detector. The separation efficiency of these ions by IMS and CE is improved by using specific shifting agents (18-Crown-6 Ether) selective to only one of these ions. This strategy has successfully separated the two isobaric ions present and leads to the structural elucidation of the isobar contaminant of SeMet. [less ▲]

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See detailInnovative analytical strategy using ion-mobility for structural or functional selenium isomers identification by ion mobility spectrometry
Far, Johann ULg; Kune, Christopher ULg; Lobinski, Ryszard et al

Poster (2013, July)

Selenium (Se) is a trace element which is both essential and toxic depending on its concentration and its chemical form. Se-rich yeast is one of the most popular Se source for supplementation. The ... [more ▼]

Selenium (Se) is a trace element which is both essential and toxic depending on its concentration and its chemical form. Se-rich yeast is one of the most popular Se source for supplementation. The classical method of speciation is related to multidimensional liquid chromatography (LC) hyphenated to mass spectrometry (MS) Recent advances in Se speciation led to greatly improve the Se speciation in these samples but isomers identification and quantification remain challenging. This work focuses on the elaboration of an innovative analytical strategy for the detection and the structural elucidation of isobaric selenium compounds present in Se-rich yeast. A specific complex formation agent acts as a chemical probe for the detection of chemical function. The addition of a complexing agent can improve the discrimination between structural or functional Se isomers using ion mobility techniques as Ion Mobility Spectrometry (IMS) by increasing the molecular weight (i.e. the m/z ratio in MS) and the collision cross section of a target ion after selective complexation. This Ion Mobility orthogonal separation improves the structural elucidation. Crown ethers used as shifting agents can specifically form complexes with primary amines. The addition of crown ether to different low molecular weight fractions obtained by multidimensional LC of a water extract from Se-rich yeast permitted to detect Se isomers and confirmed their structure using IMS. [less ▲]

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See detailDevelopment of an analytical strategy to measure major selenium-containing species in juvenile turtles (Trachemys scripta scripta) by SAX-HPLC-ICP MS
Far, Johann ULg; Dyc, Christelle; Das, Krishna ULg et al

Poster (2013, July)

Sea turtles are exposed to many environmental elements such as selenium (Se). Sea turtles are listed under the Red List of threatened species by the International Union for Conservation of Nature. It is ... [more ▼]

Sea turtles are exposed to many environmental elements such as selenium (Se). Sea turtles are listed under the Red List of threatened species by the International Union for Conservation of Nature. It is thus mandatory to use low-invasive tissue collection (skin, carapace, blood ) for estimating Se exposure in these highly protected turtles. For this purpose, a biological modal Trachemys scripta scripta (or slider turtle) was selected. For two months, juvenile turtles were dietary exposed to Se by spiking the food with Selenomethionine (SeMet) or Methionine as control groups. Individuals were sacrificed after different time of exposure and tissues (skin, liver, muscle, carapace and blood) collected to perform Se speciation and determine some biological endpoints. An analytical strategy was developed to cope with the very low amount of available sample. It is briefly consisting by reduction, alkylation and proteolysis of the entire freeze-dried tissues followed by sample clean-up using ultra-filtration membrane. Then anion exchange HPLC using salt and pH gradient was developed to prevent the introduction of organic solvents, which cause severe fooling of ICP MS and avoid ultra-trace analyses of sea water in routine analysis. This method successfully achieved the detection and quantification at ppm level of expected species (i.e SeMet, selenocysteine, inorganic Se) and also unknown species but their relative amounts were time and tissues dependent. [less ▲]

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See detailTowards Lipidomics of Low-Abundant Species for Exploring Tumor Heterogeneity Guided by High-Resolution Mass Spectrometry Imaging
Cimino, Jonathan ULg; Calligaris, David; Far, Johann ULg et al

in International Journal of Molecular Sciences (2013), 14

Many studies have evidenced the main role of lipids in physiological and also pathological processes such as cancer, diabetes or neurodegenerative diseases. The identification and the in situ localization ... [more ▼]

Many studies have evidenced the main role of lipids in physiological and also pathological processes such as cancer, diabetes or neurodegenerative diseases. The identification and the in situ localization of specific low-abundant lipid species involved in cancer biology are still challenging for both fundamental studies and lipid marker discovery. In this paper, we report the identification and the localization of specific isobaric minor phospholipids in human breast cancer xenografts by FTICR MALDI imaging supported by histochemistry. These potential candidates can be further confirmed by liquid chromatography coupled with electrospray mass spectrometry (LC-ESI-MS) after extraction from the region of interest defined by MALDI imaging. Finally, this study highlights the importance of characterizing the heterogeneous distribution of low-abundant lipid species, relevant in complex histological samples for biological purposes. [less ▲]

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See detailPotential of CE/MS for Small Carboxylic Acids Analysis as Alternative to GC/MS Reference Analytical Methods
Far, Johann ULg; Falmagne, Jean-Bernard, ANALIS R&D; de l'Escaille, François, ANALIS R&D et al

Poster (2012, October)

GC/MS (Gas Chromatography coupled to Mass Spectrometry) is the analytical method of choice for carboxylic acids analysis because of good sensitivity, low limit of detection and the possibility to compare ... [more ▼]

GC/MS (Gas Chromatography coupled to Mass Spectrometry) is the analytical method of choice for carboxylic acids analysis because of good sensitivity, low limit of detection and the possibility to compare the pattern of fragmentation with existing databases for identification. However GC requires that the analytes are volatile. If it is not the case, the use of chemicals in order to perform the derivatization is mandatory, this may induce analytical bias. CE (Capillary electrophoresis) is a technique of choice for ions separation without prior treatments. The method is fast and do not require highly technical skills. A UV detector is the most common detection method; however electrospray mass spectrometry detection is recently gaining interest, while it really helps for structural information of the detected compounds. In this poster, the preliminary results of CE/MS analysis of several carboxylic acids are presented. All carboxylic acids are analyzed without any sample pretreatment. These acids looked at are from the “Citric Acid Cycle” including pyruvate and some isotope labeled analogues but also glyoxylate, lactate, oxalate and tartrate. Moreover, the preliminary results of a sample preparation approach to remove phosphate salts are presented. Phosphate is a very common salt that is often used in biological buffers but prevents the derivatization of carboxylic acid for GC/MS analysis and reduces the reproducibility of results for both GC/MS and CE/MS analysis. [less ▲]

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See detailLarge-scale identification of selenium metabolites by online size-exclusion-reversed phase liquid chromatography with combined inductively coupled plasma (ICP-MS) and electrospray ionization linear trap-Orbitrap mass spectrometry (ESI-MS(n))
Preudhomme, Hugues; Far, Johann ULg; Gil-Casal, Sandra et al

in Metallomics (2012), 4(5), 422-432

A method was developed for the comprehensive cartography of the selenium metabolites synthesized in the process of conversion of selenite [Se(IV)] into organic compounds and enrichment of yeast with ... [more ▼]

A method was developed for the comprehensive cartography of the selenium metabolites synthesized in the process of conversion of selenite [Se(IV)] into organic compounds and enrichment of yeast with selenium. The number of compounds detected was considerably increased (49) owing to the optimization of the fractionation procedure and the use of UPLC. The increased purity of the minor selenoorganic amino acids and oligopeptides allowed successful on-line de-novo identification based on the exact mass (o1 ppm) and fragmentation (MS2/MS3) mass spectra obtained with high resolution and high mass accuracy. The quality of mass spectra allowed the re-interpretation of previously reported structures of some selenium species. [less ▲]

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See detailThe usefulness of Ion Mobility-Mass Spectrometry for Small Molecules Analysis
Far, Johann ULg; Goscinny, Séverine ULg; Joly, Laure et al

Conference (2012, March)

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See detailRecent advances in analytical chemistry and mass spectrometry for organic selenium and tellurium compounds
Far, Johann ULg; De Pauw, Edwin ULg; Eppe, Gauthier ULg

in Rappoport, Zvi (Ed.) The Chemistry of Organic Selenium and Tellurium compounds Volume 3 Part 1 and 2 (2012)

The objective of this chapter is to present the recent developments in mass spectrometry for selenium (Se) and tellurium (Te) analysis. The state-of-the-art of mass spectrometry based techniques available ... [more ▼]

The objective of this chapter is to present the recent developments in mass spectrometry for selenium (Se) and tellurium (Te) analysis. The state-of-the-art of mass spectrometry based techniques available is critically evaluated with particular emphasis in ion sources and mass analyzers. The complexity of identification and characterization of Se, Te species including their speciation in the environment or in biological materials requires methodologies not only limited to mass spectrometry. Particular attention is given to sample preparation and hyphenated techniques with mass spectrometry for a comprehensive characterization of these trace elements. All these aspects are illustrated with up-to-date applications from the literature. Finally, future trends in mass spectrometry give the readers new insights in Se and Te species detection. [less ▲]

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See detailMass spectrometry applied to biomolecules analysis
Far, Johann ULg; Mazzucchelli, Gabriel ULg; Meuwis, Marie-Alice ULg et al

Conference (2011, March 31)

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See detailStudy of the Se-containing metabolomes in Se-rich yeast by size-exclusion-cation-exchange HPLC with the parallel ICP MS and electrospray orbital ion trap detection
Casal, S. G.; Far, Johann ULg; Bierla, K. et al

in Metallomics (2010), 2(8), 535-548

Strong cation exchange HPLC with the parallel ICP MS and electrospray hybrid linear ion trap quadrupole orbital trap mass spectrometry (ESI Orbitrap MS) detection was developed for the study of the ... [more ▼]

Strong cation exchange HPLC with the parallel ICP MS and electrospray hybrid linear ion trap quadrupole orbital trap mass spectrometry (ESI Orbitrap MS) detection was developed for the study of the metabolomic pattern of selenium in selenium-rich yeast. The mobile phase composition (gradient of ammonium formate in 20% methanol) was optimized to obtain separation in conditions guaranteeing the identical ICP MS sensitivity during the entire chromatographic run and the compatibility with electrospray ionization. Twenty seven Se-containing metabolites observed in the HPLC-ICP MS chromatogram were identified by ESI Orbitrap MS based on the Se isotopic pattern, the accurate molecular mass, and the multistage fragmentation patterns. The method allowed for the first time the correlation of the differences observed in HPLC-ICP MS chromatography of water extracts of Se-rich yeast samples from different manufacturers with the identity of the eluted compounds determined by ESI MS. [less ▲]

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See detailDetermination of the selenium isotopic compositions in Se-rich yeast by hydride generation-inductively coupled plasma multicollector mass spectrometry
Far, Johann ULg; Berail, S.; Preud'homme, H. et al

in Journal of Analytical Atomic Spectrometry [=JAAS] (2010), 25(11), 1695-1703

A method was developed for the precise determination of selenium isotopic compositions (delta Se-82/77, delta Se-82/76 and delta Se-82/74) by hydride generation inductively coupled plasma multiple ... [more ▼]

A method was developed for the precise determination of selenium isotopic compositions (delta Se-82/77, delta Se-82/76 and delta Se-82/74) by hydride generation inductively coupled plasma multiple collector mass spectrometry (HG-MC ICP MS) in Se-rich yeast. The conversion of all the selenium forms into Se(IV) during digestion and reduction steps was investigated by anion-exchange ICP quadrupole MS (SAX ICP Q MS) and was found to be complete. Measurement precision values expressed as deltas (delta) with regard to NIST SR M3149 were between 0.2-0.4 parts per thousand (2SD) over a period of 6 months for 25 or 50 ng mL(-1) of introduced selenium. The application of the method to the analysis of nine Se-rich yeast supplements from different manufactures showed significant variations in the isotope ratios suggesting that the latter can be an attractive parameter for the yeast provenance discrimination. [less ▲]

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See detailDetection and identification of hydrophilic selenium compounds in selenium-rich yeast by size exclusion-microbore normal-phase HPLC with the on-line ICP-MS and electrospray Q-TOF-MS detection
Far, Johann ULg; Preud'homme, Hugues; Lobinski, Ryszard

in Analytica Chimica Acta (2010), 657(2),

Normal-phase HPLC and hydrophilic interaction HPLC (HILIC) were investigated for the separation of selenometabolites in a water extract of Se-rich yeast prior to their detection by ICP-MS and ... [more ▼]

Normal-phase HPLC and hydrophilic interaction HPLC (HILIC) were investigated for the separation of selenometabolites in a water extract of Se-rich yeast prior to their detection by ICP-MS and identification by electrospray MS/MS. The targeted fraction was a low-abundant fraction co-eluting with salt and sulfur analogues in size-exclusion chromatography which has so far been inaccessible to Se speciation studies. The optimization of the separation conditions resulted in the highest separation efficiency when HILIC was used and elution was carried out isocratically with a low concentration ammonium acetate buffer (1 mM ammonium acetate/10mM acetic acid) in 80% acetonitrile. Out of 15 peaks observed with the Se-specific ICP-MS detection 12 was identified by electrospray Q-TOF MS/MS (2,3-dihydroxypropionyl (DHP)-Se-methylselenocysteine [M+H](+): 272, Se-methyl-gamma-glutamyl-selenocysteinylglycine dioxide [M+H](+): 402, gamma-glutanlyl-Se-methylselenocysteine[M+H](+): 313; isomers of gamma-glutamylselenocystathionine [M+H](+): 400; Se-methyl-selenoglutathione [M+H](+): 370, isomers of N-acetylselenocystathionine [M+H](+): 313, 2,3-DHP-selenohomolanthionine [M+H](+): 373, isomers of 2,3-DHP-seienocystathionine[M+H](+): 359,2,3-DHP-selenolanthionine [M+H](+): 345 and selenohomolanthionine [M+H](+): 285). (C) 2009 Elsevier B.V. All rights reserved. [less ▲]

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See detailIdentification of anionic selenium species in Se-rich yeast by electrospray QTOF MS/MS and hybrid linear ion trap/orbitrap MSn
Dernovics, M.; Far, Johann ULg; Lobinski, R.

in Metallomics (2009), 1(4), 317-329

An analytical approach allowing the identification Of unknown selenium metabolites ill selenium-rich yeast was described. Anion-exchange HPLC of the Se-metabolome fraction co-eluting with salts ill size ... [more ▼]

An analytical approach allowing the identification Of unknown selenium metabolites ill selenium-rich yeast was described. Anion-exchange HPLC of the Se-metabolome fraction co-eluting with salts ill size-exclusion chromatography allowed the separation of nine selenium species (excluding isomers and selenate) as monitored by inductively Coupled plasma mass spectrometry (ICP MS). The individual fractions were analyzed by electrospray QTOF MS/MS and hybrid linear ion trap/Orbitrap MSn after sample introduction by reversed-phase nanoHPLC and by hydrophilic interaction LC (HILIC), respectively. Out of the nine detected species. eight were identified oil the basis of accurate mass measurements and collision induced dissociation/fragmentation information. Seven Se-species (selenohomolanthionine, gamma-Glu-selenocystathionine, 2,3-DHP-selenocystathionine, N-acetyl-selenocystathionine, 2,3-DHP-selenohomolanthionine Se-methyl-selenoglutathione, and 2,3-DHP-Se-methylselenocysteine) were reported for the first time in Se-rich yeast. five of them have never been reported in any biological sample before. [less ▲]

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