The Experts below are selected from a list of 68880 Experts worldwide ranked by ideXlab platform
Wolfgang Schrader - One of the best experts on this subject based on the ideXlab platform.
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optimized asphaltene separation by online coupling of size exclusion chromatography and ultrahigh Resolution Mass Spectrometry
Fuel, 2018Co-Authors: Lilla Molnarne Guricza, Wolfgang SchraderAbstract:Abstract The asphaltene fraction is the heaviest part of a crude oil and is obtained as the fraction which contains compounds that are not soluble in paraffinic solvents such as n -heptane. Due to the limited solubility the use of separation methods is strongly reduced to methods that include solvents that dissolve asphaltenes. Here, the direct coupling of size exclusion chromatography with ultrahigh Resolution Mass Spectrometry to investigate the separation of asphaltenes is accomplished. Different mobile phase systems have been investigated using THF and different mixtures of chloroform and toluene to optimize the separation conditions. Due to the separation the complexity of the asphaltene sample can be reduced, therefore Mass spectra with increased information depth can be obtained due to the smaller amount of interacting species. Additionally, correlations can be proposed between molecular Mass and structural characteristics of highly condensed aromatic molecules: compounds having both aromatic core and long aliphatic chains with higher Masses were detected earlier and the smaller ones containing mostly highly aromatic structures and only a low amount of short alkyl chains (with the same DBE values) have stronger retention. Different experimental conditions such as stationary phase and mobile phase of asphaltene separation with size exclusion chromatography are investigated.
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argentation chromatography coupled to ultrahigh Resolution Mass Spectrometry for the separation of a heavy crude oil
Journal of Chromatography A, 2017Co-Authors: Lilla Molnarne Guricza, Wolfgang SchraderAbstract:Simplification of highly complex mixtures such as crude oil by using chromatographic methods makes it possible to get more detailed information about the composition of the analyte. Separation by argentation chromatography can be achieved based on the interaction of different strength between the silver ions (Ag+) immobilized through a spacer on the silica gel surface and the π-bonds of the analytes. Heavy crude oils contain compounds with a high number of heteroatoms (N, O, S) and a high degree of unsaturation thus making them the perfect analyte for argentation chromatography. The direct coupling of argentation chromatography and ultrahigh-Resolution Mass Spectrometry allows to continuously tracking the separation of the many different compounds by retention time and allows sensitive detection on a molecular level. Direct injection of a heavy crude oil into a ultrahigh-Resolution Mass spectrometer showed components with DBE of up to 25, whereas analytes with DBE of up to 35 could be detected only after separation with argentation chromatography. The reduced complexity achieved by the separation helps increasing the information depth.
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new separation approach for asphaltene investigation argentation chromatography coupled with ultrahigh Resolution Mass Spectrometry
Energy & Fuels, 2015Co-Authors: Lilla Molnarne Guricza, Wolfgang SchraderAbstract:Argentation chromatography has been developed for the analysis and separation of asphaltenes. The separation is based on the interaction between the silver ions (Ag+) bonded to a silica gel surface and the π-systems of the polycondensed aromatic compounds, where the interactions can be different when heteroatoms (N, O, S) are present in the molecules. Online coupling of argentation chromatography and high-Resolution Mass Spectrometry allows fast and detailed analysis of the separation of crude oil asphaltenes. Highly condensed aromatic compounds possessing a high degree of unsaturation can be successfully separated using a mixture of toluene and chloroform (7:3 v/v) as mobile phase and dimethyl sulfoxide as competitive ligand for elution of asphaltene compounds with double bond equivalents (DBE) of up to 40. Making use of the different structural features of the components, it is possible to separate isomeric compounds that interact with different strengths with the stationary phase. The composition of mo...
Lilla Molnarne Guricza - One of the best experts on this subject based on the ideXlab platform.
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optimized asphaltene separation by online coupling of size exclusion chromatography and ultrahigh Resolution Mass Spectrometry
Fuel, 2018Co-Authors: Lilla Molnarne Guricza, Wolfgang SchraderAbstract:Abstract The asphaltene fraction is the heaviest part of a crude oil and is obtained as the fraction which contains compounds that are not soluble in paraffinic solvents such as n -heptane. Due to the limited solubility the use of separation methods is strongly reduced to methods that include solvents that dissolve asphaltenes. Here, the direct coupling of size exclusion chromatography with ultrahigh Resolution Mass Spectrometry to investigate the separation of asphaltenes is accomplished. Different mobile phase systems have been investigated using THF and different mixtures of chloroform and toluene to optimize the separation conditions. Due to the separation the complexity of the asphaltene sample can be reduced, therefore Mass spectra with increased information depth can be obtained due to the smaller amount of interacting species. Additionally, correlations can be proposed between molecular Mass and structural characteristics of highly condensed aromatic molecules: compounds having both aromatic core and long aliphatic chains with higher Masses were detected earlier and the smaller ones containing mostly highly aromatic structures and only a low amount of short alkyl chains (with the same DBE values) have stronger retention. Different experimental conditions such as stationary phase and mobile phase of asphaltene separation with size exclusion chromatography are investigated.
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argentation chromatography coupled to ultrahigh Resolution Mass Spectrometry for the separation of a heavy crude oil
Journal of Chromatography A, 2017Co-Authors: Lilla Molnarne Guricza, Wolfgang SchraderAbstract:Simplification of highly complex mixtures such as crude oil by using chromatographic methods makes it possible to get more detailed information about the composition of the analyte. Separation by argentation chromatography can be achieved based on the interaction of different strength between the silver ions (Ag+) immobilized through a spacer on the silica gel surface and the π-bonds of the analytes. Heavy crude oils contain compounds with a high number of heteroatoms (N, O, S) and a high degree of unsaturation thus making them the perfect analyte for argentation chromatography. The direct coupling of argentation chromatography and ultrahigh-Resolution Mass Spectrometry allows to continuously tracking the separation of the many different compounds by retention time and allows sensitive detection on a molecular level. Direct injection of a heavy crude oil into a ultrahigh-Resolution Mass spectrometer showed components with DBE of up to 25, whereas analytes with DBE of up to 35 could be detected only after separation with argentation chromatography. The reduced complexity achieved by the separation helps increasing the information depth.
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new separation approach for asphaltene investigation argentation chromatography coupled with ultrahigh Resolution Mass Spectrometry
Energy & Fuels, 2015Co-Authors: Lilla Molnarne Guricza, Wolfgang SchraderAbstract:Argentation chromatography has been developed for the analysis and separation of asphaltenes. The separation is based on the interaction between the silver ions (Ag+) bonded to a silica gel surface and the π-systems of the polycondensed aromatic compounds, where the interactions can be different when heteroatoms (N, O, S) are present in the molecules. Online coupling of argentation chromatography and high-Resolution Mass Spectrometry allows fast and detailed analysis of the separation of crude oil asphaltenes. Highly condensed aromatic compounds possessing a high degree of unsaturation can be successfully separated using a mixture of toluene and chloroform (7:3 v/v) as mobile phase and dimethyl sulfoxide as competitive ligand for elution of asphaltene compounds with double bond equivalents (DBE) of up to 40. Making use of the different structural features of the components, it is possible to separate isomeric compounds that interact with different strengths with the stationary phase. The composition of mo...
Lili Yang - One of the best experts on this subject based on the ideXlab platform.
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congener specific determination of ultratrace levels of chlorinated and brominated polycyclic aromatic hydrocarbons in atmosphere and industrial stack gas by isotopic dilution gas chromatography high Resolution Mass Spectrometry method
Journal of Chromatography A, 2017Co-Authors: Rong Jin, Guorui Liu, Minghui Zheng, Heidelore Fiedler, Xiaoxu Jiang, Lili YangAbstract:Isotopic dilution gas chromatography combined with high Resolution Mass Spectrometry (GC/HRMS) has overwhelming advantages with respect to the accuracy of congener-specific ultratrace analysis of c ...
Hans H Maurer - One of the best experts on this subject based on the ideXlab platform.
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review lc coupled to low and high Resolution Mass Spectrometry for new psychoactive substance screening in biological matrices where do we stand today
Analytica Chimica Acta, 2016Co-Authors: Markus R Meyer, Hans H MaurerAbstract:The field of new psychoactive substances (NPS) is highly dynamic and the situation changes from year to year. Therefore, the current review provides a timely update about the latest developments to help analysts keep the pace with NPS distribution. It covers PubMed-listed studies published between January 2014 and January 2016 dealing with the application of liquid chromatography (LC) coupled low- and high-Resolution Mass Spectrometry (MS) for broad screenings for NPS in clinical (CT) and forensic (FT) toxicology. Latest developments and applications are highlighted and selected papers critically discussed. Comprehensive tables summarizing all discussed articles complete the overview. Finally, an outlook on the future of LC coupled MS in CT and FT is provided and readers will learn why low-Resolution Mass Spectrometry might remain the standard for the next couple of years at least for easy-to-use quantitative screening procedures.
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what is the future of ultra high performance liquid chromatography coupled to low and high Resolution Mass Spectrometry for toxicological drug screening
Journal of Chromatography A, 2013Co-Authors: Hans H MaurerAbstract:This paper reviews critically LC-MS approaches for toxicological drug screening using (ultra) high performance liquid chromatography (UHPLC) coupled to low and high Resolution Mass Spectrometry (HRMS) published since 2010. A concluding discussion focuses on progress and current status of sample workup, separation by HPLC vs. UHPLC, MS detection modes and their specificity, universality of LC-MS libraries, and validation necessary of LC-MS for screening methods. Finally, a discussion on what the future holds for LC-MS drug screening in clinical and forensic toxicology completes this review article.
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perspectives of liquid chromatography coupled to low and high Resolution Mass Spectrometry for screening identification and quantification of drugs in clinical and forensic toxicology
Therapeutic Drug Monitoring, 2010Co-Authors: Hans H MaurerAbstract:This article reviews papers on the use of liquid chromatography coupled to low- and high-Resolution Mass Spectrometry in clinical and forensic toxicology. They cover procedures for target and for more comprehensive screening for drugs (of abuse), identification of drug metabolites, and multianalyte procedures for quantification of drugs and/or their metabolites in body samples. Besides a critical overview, perspectives are discussed.
Massimo Castagnola - One of the best experts on this subject based on the ideXlab platform.
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thymosin fraction 5 re evaluated after 35 years by high Resolution Mass Spectrometry
Expert Opinion on Biological Therapy, 2018Co-Authors: Ewald Hannappel, Federica Iavarone, Massimo CastagnolaAbstract:Objectives: We reevaluated a lyophilized sample of thymosin fraction 5, stored for 37 years at room temperature, by high-Resolution Mass Spectrometry in terms of stability and yet uncharacterized p...
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Thymosin fraction 5 re-evaluated after 35 years by high-Resolution Mass Spectrometry
2018Co-Authors: Ewald Hannappel, Federica Iavarone, Massimo CastagnolaAbstract:Objectives: We reevaluated a lyophilized sample of thymosin fraction 5, stored for 37 years at room temperature, by high-Resolution Mass Spectrometry in terms of stability and yet uncharacterized polypeptides that could be biological important substances. Methods: A top–down proteomic platform based on high-performance liquid chromatography (HPLC) coupled to high-Resolution LTQ-Orbitrap Mass Spectrometry (MS) was applied to molecular characterization of polypeptides present in thymosin fraction 5. Results: We detected more than 100 monoisotopic Masses corresponding to thymosin β4 and truncated forms of ubiquitin, prothymosin α, thymosin β4, and thymosin β9. Additionally, we discovered a new polypeptide present in thymosin fraction 5 and identified it as intact SH3 domain-binding glutamic acid-rich-like protein 3. Conclusion: In spite of the well-known proteolytic processes inherent to the preparation of thymosin fraction 5, still uncharacterized polypeptides as well as truncated forms of already well-known thymosins are present in fraction 5 after long-term storage. Therefore, continuing characterization of thymosin fraction 5 is even nowadays highly promising.