Littérature scientifique sur le sujet « Isomer identification »
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Articles de revues sur le sujet "Isomer identification"
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Zhang, Bolong, Jegadesan Subbiah, David J. Jones et Wallace Wing Ho Wong. « Separation and identification of indene–C70 bisadduct isomers ». Beilstein Journal of Organic Chemistry 12 (6 mai 2016) : 903–11. http://dx.doi.org/10.3762/bjoc.12.88.
Texte intégralRésumé :
Following an initial work on the isolation of a single geometric isomer from an indene–C70 bisadduct (IC70BA) mixture, we report the full fractionation and identification of the bisadduct species in the material. Eleven fractions of IC70BA isomers were separated by high-performance liquid chromatography. A number of fractions contained relatively pure isomer species and their configuration were deduced using a variety of analytical techniques including 1H and 13C NMR and UV–vis spectroscopy. The electrochemical properties and the organic solar cell device performance were investigated for fractions where a reasonable quantity of sample could be isolated.
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Yeston, J. S. « CHEMISTRY : Isomer Identification ». Science 309, no 5743 (23 septembre 2005) : 1969a. http://dx.doi.org/10.1126/science.309.5743.1969a.
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Gosar, Amit, Tabrez Shaikh et Atharva Sindwani. « Fourier Transform Infrared (FTIR) Spectroscopic Analysis of Amino Acid Serine for its Chiral Identification ». Journal of Pharmaceutical Quality Assurance and Quality Control 4, no 1 (14 avril 2022) : 1–4. http://dx.doi.org/10.46610/jqaqc.2022.v04i01.001.
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Synthesis of chiral drugs required chiral starting materials organic compounds. DL serine is an amino acid that is used as a key starting material in the synthesis of many drug substances. D or L isomer of Serine will lead to the chiral drug substances whereas DL mixture will lead to racemic drug substances. FTIR can be used as the primary analytical tool for the identification of Serine isomers and its racemic mixture. Many absorption bands in FTIR spectra identify whether a molecule is a specific isomer or racemic mixture. A systematic comparison of FTIR spectroscopic data is carried out revealing that the compound is the specific isomer and the racemic mixture shows different spectra with different bands.
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Delmonte, Pierluigi, Martin P. Yurawecz, Magdi M. Mossoba, Cristina Cruz-Hernandez et John K. G. Kramer. « Improved Identification of Conjugated Linoleic Acid Isomers Using Silver-Ion HPLC Separations ». Journal of AOAC INTERNATIONAL 87, no 2 (1 mars 2004) : 563–68. http://dx.doi.org/10.1093/jaoac/87.2.563.
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Abstract Silver-ion high-performance liquid chromatography (Ag+-HPLC) has been shown to be effective in the resolution of most of the isomers of conjugated octadecadienoic acids (18:2), also known as conjugated linoleic acid (CLA). The CLA isomers identified in natural fats from ruminants are a mixture of numerous positional and geometric isomers from 7,9- to 12,14–18:2. Ag+-HPLC separates both geometric (trans,trans < cis/trans < cis,cis) and positional CLA isomers using the mobile phase hexane/acetonitrile (99.9:0.1). The elution volumes for the CLA isomers were not only affected by the concentration of acetonitrile (in the prepared mobile phase) but also with successive runs during the day using a prepared mobile phase batch, due to the partial solubility of acetonitrile in hexane. However, this drift does not affect the relative resolution of the CLA isomers. The addition of diethyl ether to the mobile phase partly stabilizes the solvent mixture. In order to facilitate the interpretation of Ag-+HPLC chromatograms, the relative retention volumes (RRV) were calculated for each CLA isomer. Toluene was added to all the test portions and served as an estimator of dead volume, whereas the elution of the ubiquitous 9c,11t-CLA isomer was chosen as unity (1.00). Expressing the elution of all the CLA isomers as their RRV greatly helped to standardize each CLA isomer, resulting in relatively small coefficients of variation (% CV) for the trans,trans (<1.5%) and cis/trans (<0.5%) CLA isomers. The identification of the CLA isomers was further facilitated by synthesis of authentic CLA isomers. All the geometric CLA fatty acid methyl esters (FAME) from positions 6,8- to 13,15-CLA were commercially available or synthesized by a combination of partial hydrazine reduction of known polyunsaturated fatty acids followed by alkali isomerization, isolation of products, and further iodine-catalyzed geometric isomerization. Based on expressing the elution volume as RRV and the availability of the synthetic CLA isomers, a unique reversal of the elution order of the c/t CLA isomers was found. It is also proposed that the retention times of CLA isomers by gas chromatography (GC) should be expressed as their relative retention times (RRT) relative to methyl γ-linoleneate. The availability of CLA reference materials and the application of RRV and RRT to Ag+-HPLC and GC separations, respectively, will greatly improve in the identifications of CLA isomers.
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Yurawecz, Martin P., Jo-Yun T. Chen et Bartholomew J. Puma. « Identification of cis- and trans-1,1,2,3,4-PentachIoro-4-[1-methylethoxy]-l,3-butadiene Residues in Mississippi River Fish ». Journal of AOAC INTERNATIONAL 69, no 4 (1 juillet 1986) : 586–91. http://dx.doi.org/10.1093/jaoac/69.4.586.
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Abstract The cis- and trans-isomers of 1,1,2,3,4-pentachloro-4-[1-methylethoxy]-1,3-butadiene have been identified as contaminants in fish caught from the Mississippi River at St. Louis, MO, and as far as 150 miles south of that location. Up to 0.1 ppm of the cis-isomer and 0.8 ppm of the trans-isomer were determined by using a method based on the AOAC multiresidue method for detecting organochlorine and organophosphorus pesticides. In tests of the modified AOAC method on spiked fish, both isomers were quantitatively recovered (95-106%). A mixture of the cis- and trans-isomers was synthesized by reacting hexachlorobutadiene with sodium isopropoxide. Separation of the reaction products by Florisil column chromatography provided reference standards of the individual isomers for identification and quantitation of the residues. The stereospecificity of the synthesis reaction and the infrared and mass spectral data used to verify the structures of the products are discussed.
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Sobhi, Hany F., Xinjie Zhao, Peter Plomgaard, Miriam Hoene, Jakob S. Hansen, Benedikt Karus, Andreas M. Niess et al. « Identification and regulation of the xenometabolite derivatives cis- and trans-3,4-methylene-heptanoylcarnitine in plasma and skeletal muscle of exercising humans ». American Journal of Physiology-Endocrinology and Metabolism 318, no 5 (1 mai 2020) : E701—E709. http://dx.doi.org/10.1152/ajpendo.00510.2019.
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Little is known about xenometabolites in human metabolism, particularly under exercising conditions. Previously, an exercise-modifiable, likely xenometabolite derivative, cis-3,4-methylene-heptanoylcarnitine, was reported in human plasma. Here, we identified trans-3,4-methylene-heptanoylcarnitine, and its cis-isomer, in plasma and skeletal muscle by liquid chromatography-mass spectrometry. We analyzed the regulation by exercise and the arterial-to-venous differences of these cyclopropane ring-containing carnitine esters over the hepatosplanchnic bed and the exercising leg in plasma samples obtained in three separate studies from young, lean and healthy males. Compared with other medium-chain acylcarnitines, the plasma concentrations of the 3,4-methylene-heptanoylcarnitine isomers only marginally increased with exercise. Both isomers showed a more than twofold increase in the skeletal muscle tissue of the exercising leg; this may have been due to the net effect of fatty acid oxidation in the exercising muscle and uptake from blood. The latter idea is supported by a more than twofold increased net uptake in the exercising leg only. Both isomers showed a constant release from the hepatosplanchnic bed, with an increased release of the trans-isomer after exercise. The isomers differ in their plasma concentration, with a four times higher concentration of the cis-isomer regardless of the exercise state. This is the first approach studying kinetics and fluxes of xenolipid isomers from tissues under exercise conditions, supporting the hypothesis that hepatic metabolism of cyclopropane ring-containing fatty acids is one source of these acylcarnitines in plasma. The data also provide clear evidence for an exercise-dependent regulation of xenometabolites, opening perspectives for future studies about the physiological role of this largely unknown class of metabolites.
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Gal, Joseph. « New Single-Isomer Compounds on the Horizon ». CNS Spectrums 7, S1 (avril 2002) : 45–54. http://dx.doi.org/10.1017/s1092852900028601.
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ABSTRACTIn 1992, the Food and Drug Administration (FDA) issued new guidelines governing stereoisomerism in new-drug development. The guidelines strongly encourage the development of single isomers and discourage stereoisomeric (eg, racemic) mixtures. As a result, most new chiral drugs are being developed as single enantiomers (ie, single isomers). There are three mechanisms for the identification and development of new single-isomer drugs: chiral switches (CS), chiral metashifts (CM), and new single-isomer chemical entities (NSICEs). In a CS, one of the two enantiomers of an established racemate is developed as a new drug, with the expectation that the single-isomer form has advantages over the racemic parent in terms of efficacy and/or adverse effects. Many new CS drugs are in development, eg, (S)-oxybutynin for urinary incontinence and escitalopram for depression. In a CM, a chiral metabolite of a drug is developed, in single-isomer form, as an agent with advantages over the parent. Among the current CM drugs in development are (+)-norcisapride (safer GI prokinetic agent than the racemic parent cisapride) and (S)-desmethylzopiclone (antianxiety agent, metabolite of the sedative-hypnotic zopi-clone). Many NSICEs are in development, eg, rosuvastatin as an antihypercholesterolemic, posaconazole as an antifungal, sitafloxacin as a fluoroquinolone antibacterial, pregabalin as an anticonvulsant, abarelix as an antineoplastic, etc. As in the development of any new drug, not every single-isomer candidate will reach the clinic, but there is no doubt that the move to single-isomer agents is an important step forward in the search for better and safer drugs.
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Baumgard, Lance H., Benjamin A. Corl, Debra A. Dwyer, A. Saebø et Dale E. Bauman. « Identification of the conjugated linoleic acid isomer that inhibits milk fat synthesis ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 278, no 1 (1 janvier 2000) : R179—R184. http://dx.doi.org/10.1152/ajpregu.2000.278.1.r179.
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Conjugated linoleic acids (CLA) are octadecadienoic fatty acids that have profound effects on lipid metabolism. Our previous work showed that CLA (mixture of isomers) markedly reduced milk fat synthesis. In this study, our objective was to evaluate the effects of specific CLA isomers. Multiparous Holstein cows were used in a 3 × 3 Latin square design, and treatments were 4-day abomasal infusions of 1) skim milk (control), 2) 9,11 CLA supplement, and 3) 10,12 CLA supplement. CLA supplements provided 10 g/day of the specific CLA isomer ( cis-9, trans-11 or trans-10, cis-12). Treatments had no effect on intake, milk yield, or milk protein yield. Only the 10,12 CLA supplement affected milk fat, causing a 42 and 44% reduction in milk fat percentage and yield, respectively. Milk fat composition revealed that de novo synthesized fatty acids were extensively reduced. Increases in ratios of C14:0 to C14:1 and C18:0to C18:1 indicated the 10,12 CLA supplement also altered Δ9-desaturase. Treatments had minimal effects on plasma concentrations of glucose, nonesterified fatty acids, insulin, or insulin-like growth factor-I. Overall, results demonstrate that trans-10, cis-12 CLA is the isomer responsible for inhibition of milk fat synthesis.
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Corvini, P. F. X., R. Vinken, G. Hommes, M. Mundt, J. Hollender, R. Meesters, H. Fr Schröder et B. Schmidt. « Microbial degradation of a single branched isomer of nonylphenol by Sphingomonas TTNP3 ». Water Science and Technology 50, no 5 (1 septembre 2004) : 189–94. http://dx.doi.org/10.2166/wst.2004.0327.
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The endocrine disrupting chemical nonylphenol (NP) is a technical product which consists of a complex mixture of nonylphenols with different alkyl side-chain isomers. Since the bio-degradation of each NP isomer may lead to its own range of metabolites, the isolation and identification of transformation products is very difficult. In order to overcome this difficulty, the nonylphenol isomer 4(3′,5′-dimethyl-3′-heptyl)-phenol (p353NP) was synthesized, and its degradation by an axenic culture of Sphingomonas TTNP3 was investigated with [ring-U-14C]-labelled and non-labelled p353NP including a time-course study. Radioactive mass balancing resulted in different polar soluble fractions, in insoluble radioactivity associated with biomass, and volatile radioactivity in the form of the mineralization product 14CO2. In the extracellular media, the presence of nonanol corresponding to the nonyl chain of the NP isomer was confirmed and its concentration was determined during the course of fermentation. No other radioactive compounds were detected beside the parent isomer. Radioactive metabolites were only found in the intracellular fraction of S. TTNP3.
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O'Neil, Constance A., Steven J. Schwartz et George L. Catignani. « Comparison of Liquid Chromatographic Methods for Determination of Cis-Trans Isomers of β-Carotene ». Journal of AOAC INTERNATIONAL 74, no 1 (1 janvier 1991) : 36–42. http://dx.doi.org/10.1093/jaoac/74.1.36.
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Abstract Four liquid chromatographic columns and various solvent systems were evaluated for their ability to resolve and quantitate cls-trans Isomers of β-carotene. The Vydac C18 201 TP and Ca(OH)2 columns were most effective in resolving alltrans-, 13-cls-, and 9-cls-β-carotenes. Additionally, the 15- c18 Isomer was separated using the method employing a Ca(OH)2 column. Peak Identification was based on absorption spectra (obtained from photodlode array data), retention times, and coelutlon in comparison to authentic standards. A quantitative analysis of vegetable extracts using both the Vydac and Ca(OH)2 columns showed comparable results. However, both procedures lacked complete resolution of 2 minor clsβ-carotenes, tentatively identified as dl-cis Isomers. High selectivity for carotene Isomers as well as fewer interferences were observed with the Ca(OH)2 procedure for analysis of plant tissue extracts and thus, It is preferred for determination of β-carotene cis-isomer content In these samples.
Thèses sur le sujet "Isomer identification"
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Ji, Xiaolong. « Hydrogen storage in dibenzyltoluene via catalytic hydrogenation and its conveyance towards acetone through transfer hydrogenation ». Electronic Thesis or Diss., Lyon 1, 2024. http://www.theses.fr/2024LYO10294.
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Cette thèse est orientée vers l'objectif d'obtenir une compréhension approfondie du stockage d'hydrogène dans les liquides organiques porteurs d'hydrogène (LOHC) via a) l'hydrogénation catalytique hétérogène et b) une alternative de l'utilisation de l'hydrogène stocké, avec la réaction d'hydrogénation par transfert reliant les LOHC et l'acétone. L'hydrogène peut être efficacement stocké dans les LOHC via l'hydrogénation et finalement restitué sous forme moléculaire par la déshydrogénation des composés riches en hydrogène. Le mélange commercial des isomères de dibenzyltoluène et benzylbenzyltoluène (H0-DBT/BBT) avec leurs molécules correspondantes riches en hydrogène, le perhydro-dibenzyltoluène et perhydro-benzylbenzyltoluène (H18-DBT/BBT), peut être valorisé grâce à sa haute capacité de stockage, la grande plage de température dans laquelle il reste sous la forme d'un liquide et sa disponibilité commerciale. Mais un aperçu détaillé des isomères du mélange, leur comportement pendant l'hydrogénation et la cinétique du stockage d'hydrogène ne sont pas bien décrits dans la littérature, alors qu'ils sont cruciaux pour la conception des réacteurs et le développement des procédés. En outre, l'endothermicité de la restitution de l'H2 demande un apport important d'énergie externe et par conséquent, entrave l'efficacité globale du procédé. Une réaction athermique d'hydrogénation par transfert entre le H18-DBT/BBT et l'acétone, qui peut avoir lieu à plus basse température que la déshydrogénation, est une solution potentielle à ce problème. Cette réaction génère de l'isopropanol en tant que produit qui peut être utilisé dans les piles à combustible à membrane échangeuse de protons. Cette thèse a été effectuée en 4 phases, la première était une étude expérimentale sur l'hydrogénation du H0-DBT/BBT avec des catalyseurs à base de Pt dans un réacteur agité sous différentes conditions de température, pression, vitesse d'agitation, ratio catalyseur/réactifs, concentration des réactifs, et de taille des particules afin d'élucider les aspects importants de la réaction incluant les éventuelles limitations par transfert. La quantification précise des produits de la réaction a été effectuée par le suivi de la consommation d'H2 et l'analyse du liquide. Dans la deuxième période du projet, une méthodologie analytique pour discriminer les isomères du mélange, regroupant la GC/MS, la spectrométrie de masse, complétée par des bilans massiques de la réaction, a été établie. Les mécanismes de fragmentation et de réarrangement ont fourni des informations importantes pour l'identification des isomères. L'attribution de la majorité des isomères présents dans le mélange a été obtenue, ce qui a été confirmé par les synthèses organiques, la chromatographie flash et l'hydrogénation des isomères de H0-DBT/BBT synthétisés. Durant la troisième phase de la thèse, basée sur les résultats obtenus des deux précédentes périodes, la modélisation rigoureuse du réacteur et de la cinétique intrinsèque a été effectuée de façon globale et sur les isomères individuels, en prenant en compte les phénomènes physiques, l'adsorption des molécules et la désactivation du catalyseur. Les modèles étaient conformes aux résultats expérimentaux et ont permis l'estimation des paramètres clés y compris les coefficients de transfert, les constantes de vitesse, les énergies d'activation et les coefficients d'adsorption. Durant la dernière phase du projet, l'hydrogénation par transfert entre le H18-DBT/BBT et l'acétone a été étudiée sous différentes conditions dans un réacteur agité conçu pour la quantification de la réaction complexe, impliquant des constituants aux propriétés physico-chimiques très différentes. Les résultats ont permis d'élucider les effets de transfert de masse, la limitation thermodynamique, les réactions secondaires et leurs mécanismes avec des catalyseurs Pt/SiO2 et Pt/C, ce qui a également permis de proposer une conception d'un procédé adaptéThe focus of this thesis is to gain a deeper understanding about the hydrogen storage inside Liquid Organic Hydrogen Carriers (LOHCs) via a) heterogeneous catalytic hydrogenation and b) an alternative to the utilization of the stored hydrogen, which is the transfer hydrogenation reaction coupling the LOHCs with acetone. Hydrogen can be efficiently stored in LOHCs through hydrogenation and later on restored to its molecular form by the dehydrogenation of the H2-rich compounds. The commercial mixture of dibenzyltoluene and benzylbenzyltoluene (H0-DBT/BBT) isomers, of which the hydrogenated form is the perhydro-dibenzyltoluene and perhydro-benzylbenzyltoluene (H18-DBT/BBT), could be valued for its high storage capacity, large liquid phase temperature range and commercial availability. But a profound insight into the isomers in the mixture, their behavior during hydrogenation and the kinetics of H2 storage are not well described in the literature, which are crucial for the reactor design and process development. Furthermore, the high endothermicity of the hydrogen release reaction requires substantial external energy input and thus hinders the global energy efficiency of the process. An athermic transfer hydrogenation reaction between H18-DBT/BBT and acetone, which could take place at much lower temperatures compared to dehydrogenation, is a potential solution to this problem. This reaction forms isopropanol as product which could be used in proton exchange membrane fuel cells. This thesis was carried out in 4 phases, of which the first was the experimental study of the hydrogenation of H0-DBT/BBT using Pt-based catalysts in a stirred tank reactor under different conditions, including temperature, pressure, stirring speed, catalyst-to-substrate ratio, reactant concentration and catalyst particle size, to elucidate the important aspects of the reaction including probable transfer limitations. The precise quantification of the reaction products was realized by the monitoring of H2 consumption and liquid analysis. In the second phase of the project, an analytical methodology for the isomer mixture regrouping GC/MS and MS spectrometry supported by reaction mass balance was successfully established. Fragmentation and rearrangement mechanisms provided important information for the identification of isomers. The attribution of the majority of the isomers present in the mixture was achieved, which was further confirmed by organic synthesis, flash chromatography and hydrogenation of synthesized pure H0-DBT/BBT isomers. During the third phase of this thesis, rigorous reactor modeling and intrinsic kinetic modeling were carried out based on the results obtained from the previous two phases both on a global scale and on each isomer, taking physical phenomenon, molecule adsorption and catalyst deactivation into account. These models were in great agreement with the experimental results and allowed the estimation of key parameters including mass transfer coefficients, rate constants, activation energies and adsorption coefficients. During the last phase of the project, the transfer hydrogenation reaction between H18-DBT/BBT and acetone was studied under various conditions in another stirred tank reactor designed for the quantification of a complex reaction of which the components had very different physico-chemical properties. The results allowed to elucidate mass transfer effects, thermodynamic limitation, side reactions and reaction mechanism with Pt/SiO2 and Pt/C catalysts, from which a suitable process concept was proposed as well
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Sundqvist, Kristina. « Sources of dioxins and other POPs to the marine environment : Identification and apportionment using pattern analysis and receptor modeling ». Doctoral thesis, Umeå universitet, Kemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-22266.
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In the studies underlying this thesis, various source tracing techniques were applied to environmental samples from the Baltic region. Comprehensive sampling and analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in surface sediments in Swedish coastal and offshore areas resulted in a unique data set for this region. Nearly 150 samples of surface sediments were analyzed for all tetra- to octa-chlorinated PCDD/Fs. The levels showed large spatial variability with hotspots in several coastal regions. Neither Sweden nor the EU has introduced guideline values for PCDD/Fs in sediment, but comparisons to available guidelines and quality standards from other countries indicate that large areas of primarily coastal sediments may constitute a risk to marine organisms. Multivariate pattern analysis techniques and receptor models, such as Principal Component Analysis (PCA) and Positive Matrix Factorization (PMF), were used to trace sources. These analyses suggested that three to six source types can explain most of the observed pattern variations found in the sediment samples. Atmospheric deposition was suggested as the most important source to offshore areas, thus confirming earlier estimates. However, spatial differences indicated a larger fraction of local/regional atmospheric sources, characterized by PCDFs, in the south. This was indicated by the identification of several patterns of atmospheric origin. In coastal areas, the influence of direct emission sources was larger, and among these, chlorophenol used for wood preservation and emissions from pulp/paper production and other wood related industry appeared to be most important. The historic emissions connected to processes involving chemical reactions with chlorine (e.g. pulp bleaching) were found to be of less importance except at some coastal sites. The analysis of PCDD/Fs in Baltic herring also revealed spatial variations in the levels and pollution patterns along the coast. The geographical match against areas with elevated sediment levels indicated that transfer from sediments via water to organisms was one possible explanation. Fugacity, a concept used to predict the net transport direction between environmental matrices, was used to explore the gas exchange of hexachlorocyclohexanes (HCHs) and polychlorinated biphenyls (PCBs) between air and water. These estimates suggested that, in the Kattegat Sea, the gaseous exchange of HCHs primarily resulted in net deposition while PCBs were net volatilized under certain environmental conditions. The study also indicated that, while the air concentrations of both PCBs and γ-HCH are mostly dependent upon the origin of the air mass, the fluctuations in α-HCH were primarily influenced by seasonal changes.
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Stoppin-Mellet, Virginie. « Identification et caracterisation fonctionnelle de la nucleation des microtubules chez les plantes superieures : mise au point d'un modele in vitro sur noyaux isoles ». Université Louis Pasteur (Strasbourg) (1971-2008), 1994. http://www.theses.fr/1994STR13174.
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In vivo, l'organisation des microtubules est regulee par des centres organisateurs des microtubules (mtocs). Un des points majeurs dans la comprehension de la dynamique des microtubules dans les cellules de plantes superieures est la caracterisation de tels centres et l'etude de leur mode d'activation. Au cours de ce travail, nous avons developpe un systeme de nucleation des microtubules in vitro. Les resultats montrent que la surface des noyaux de plantes superieures peut agir comme un mtoc. Une proteine de 100 kda, reconnue par un anticorps dirige contre le materiel pericentriolaire des cellules animales, est detectee a la surface de ces noyaux. A l'aide de ce systeme, nous avons montre que des proteines associees aux microtubules (maps), purifiees a partir de cellules de tabac en culture, favorisent la nucleation des microtubules a partir de noyaux de tabac isoles et de centrosomes animaux purifies. Elles affectent differemment l'assemblage des microtubules selon le stade du cycle cellulaire auquel elles ont ete purifiees. Par ailleurs, nous avons cherche a identifier des facteurs impliques dans la regulation de la nucleation des microtubules au cours du cycle cellulaire. Les donnees obtenues suggerent que du materiel essentiel a la nucleation des microtubules est present sous forme soluble dans les cellules de plantes superieures. Parmi ces facteurs pourraient figurer des kinases cyclines dependantes. Ces donnees sont discutees en fonction de la nucleation des microtubules dans les cellules de plantes superieures
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GRATI, M'HAMED. « Identification du gene otof, responsable de la surdite isolee recessive dfnb9 chez l'homme, et caracterisation de la proteine correspondante, l'otoferline, durant le developpement cochleaire chez la souris ». Paris 7, 2001. http://www.theses.fr/2001PA077028.
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L'audition joue un role majeur dans la communication entre individus dans la societe puisqu'elle permet la perception de la parole, vehicule du langage. Par une approche de clonage positionnel et de gene candidat, nous avons identifie le gene otof dont les mutations sont responsables de la surdite isolee autosomique recessive humaine dfnb9. Il coderait pour deux proteines, l'une de 140 et l'autre de 257 kda contenant respectivement 3 et 6 domaines c2, et un domaine transmembranaire cooh-terminal. Le gene otof et son orthologue murin otof comprennent 48 exons. Ils codent pour plusieurs transcrits generes par epissage alternatif. Nous avons decele deux mutations dans otof : (i) une mutation non sens, presumee deleter les deux formes de la proteine de leur domaine c2 cooh-terminal et de leur domaine transmembranaire ; (ii) une mutation au niveau d'un site d'epissage qui n'affecterait que la forme longue de la proteine. Cette derniere mutation demontre l'implication de la forme longue de l'otoferline dans la fonction auditive. Afin d'etudier la localisation de l'otoferline nous avons genere un anticorps contre la proteine. Les etudes d'immunohistochimie ont revele la presence de l'otoferline dans l'appareil de golgi et dans la membrane plasmique basale et baso-laterale de la cellule ciliee (cc) sensorielle interne (i) de la cochlee. Son expression au cours du developpement est parallele a la maturation des synapses des cellules sensorielles. L'expression de l'otoferline dans les pc12 a montre qu'elle serait transportee vers les terminaisons neurite-like grace a la presence de motifs d'adressage. Le profil d'expression de l'otoferline et ces domaines c2 homologues a ceux de la synaptotagminei, absente dans les cci, nous ont
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HALLOU, ABDESLEM. « Etude par spectroscopie ir de la diffusion et de la photodissociation du chlorure de nitrosyle isole en matrice. Identification et photochimie de son complexe avec la molecule d'eau ». Paris 6, 1998. http://www.theses.fr/1998PA066158.
Texte intégralRésumé :
La diffusion thermique et la photodissociation de la molecule du chlorure de nitrosyle, molecule d'interet atmospherique, ainsi que l'identification et la photochimie de son complexe avec l'eau, ont ete caracterises en matrices par spectroscopie irtf. L'etude quantitative des effets de temperature sur le spectre d'absorption de clno, a permis de caracteriser la paire formee par deux monomeres en proches voisins. L'observation, a 21k, de la disparition de la paire qui conduit essentiellement a clno monomere et, a 26k, de la formation du dimere a partir du monomere, met en evidence l'existence de deux processus de diffusion. Le premier qui se produit avec une energie d'activation de l'ordre de 4 kjmol 1 correspond au saut d'une molecule de clno de son site a un site voisin. Le deuxieme processus correspond au vrai processus de diffusion de clno dans la matrice de n 2, il conduit a la formation du dimere (clno) 2 avec une energie d'activation de l'ordre de 8 kjmol 1. La photodissociation de clno en cl et no a 266 nm n'est pas observee en matrice du fait de l'effet de cage qui conduit a la recombinaison des photofragments. Cependant, lors de la recombinaison, il se forme a la fois le chlorure de nitrosyle et son isomere clon identifie pour la premiere fois. Dans la matrice, clon se transforme en clno par un effet tunnel, plus rapide pour l'espece naturelle que pour les autres especes isotopiques. Le complexe forme entre clno et h 2o a ete identifie et sa structure determinee par un calcul de champ de force et par des calculs ab initio. Dans le complexe, l'interaction entre les deux sous-molecules se fait principalement entre l'atome d'oxygene de h 2o et l'atome d'azote de clno, l'orientation des deux sous-molecules qui se trouvent dans deux plans differents conduisant aussi a une faible liaison hydrogene entre oh et cl. L'irradiation du complexe clno:h 2o en matrice conduit a la formation de l'acide nitreux trans et du chlorure d'hydrogene, qui se trouvent en interaction dans la cage matricielle. La comparaison des frequences de ses modes normaux mesures experimentalement et calcules, par calcul ab initio, a permis de determiner sa structure la plus stable.
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AKONO, ZIBI YVES. « Pneumocystis carinii : caracterisations physicochimiques, immunochimiques, localisation ultrastructurale des antigenes constitutifs et identification des antigenes solubles libres dans la pneumocystose du lapin. relation avec les antigenes de p. carinii isoles chez l'homme et le rat ». Clermont-Ferrand 2, 1992. http://www.theses.fr/1992CLF21364.
Texte intégralRésumé :
Le present travail a porte principalement sur l'analyse de la constitution antigenique de pneumocystis carinii et sur l'interet que presentent les antigenes du parasite pour mettre en evidence l'infestation et permettre de suivre l'evolution de celle-ci au cours des differentes phases evolutives du portage parasitaire. Les etudes ont ete faites a partir de modeles de pneumocystose chez le lapin. Les proprietes physicochimiques et antigeniques des constituants de p. Carinii ont ete precisees grace a la combinaison des techniques de chromatographie sous haute pression, d'immunoempreinte, d'immunotransfert et d'immunoaffinite. Onze principaux complexes antigeniques de masses moleculaires 60 a 310 kda, dont les sous-unites polypeptidiques s'echelonnent de 27 a 170 kda, ont ete identifies. Les polypeptides de 39 kda (gp39), 45 kda (gp45), 55 kda (gp55), 65 kda (gp65) et 116 kda (gp116) portent des residus glucidiques mis en evidence grace a l'association de diverses reactions sollicitant l'activite de la concanavaline a, du bleu alcian et du periodate schiff. Une approche de la localisation cellulaire realisee par immunomarquage a l'or colloidal, indique que les epitopes portes par la gp39 se localisent principalement a l'interieur des formes kystiques tandis que ceux portes par la gp55 s'expriment a la surface et a l'interieur des kystes et trophozoites et ceux portes par la gp116 se trouvent surtout a la surface de ces organismes. La gp39 et la gp55 sont deux des constituants qui ont ete reconnus avec la plus grande frequence (plus de 65%) par les anticorps produits par les lapins au cours des trois phases evolutives du portage parasitaire. Les anticorps diriges contre ces deux constituants pourraient donc constituer des marqueurs de l'infestation. Dans les echantillons de lavage pulmonaire et de serum, un constituant de 80 kda a ete frequemment detecte dans durant les trois phases evolutives du portage parasitaire. D'autres constituants de 27 kda, 39 kda, 45 kda, 55 kda, 70 kda et 116 kda ont egalement ete identifies notamment, dans les echantillons de lavage pulmonaire de lapins massivement parasites. Parmi ces constituants, celui de 39 kda a ete le plus constant: principalement mis en evidence dans 19,27% des echantillons de serum et 66,66% des echantillons de lavage pulmonaire de lapins massivement infestes, il semble etre un candidat pour caracteriser l'infestation aigue. Enfin une premiere approche des differences et ressemblances entre constituants de p. Carinii isole chez l'homme, le lapin et le rat a ete effectuee
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Chen, Tsan Ming, et 陳燦明. « Simultaneous separation and identification of geometrical and positional carotenoid isomers ». Thesis, 1993. http://ndltd.ncl.edu.tw/handle/88612951426085477487.
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Yan, Tsun-Sheng, et 顏再生. « Identification of iturin A isomers from Bacillus amyloliquefaciens isolated in Taiwan ». Thesis, 2007. http://ndltd.ncl.edu.tw/handle/10677761812497309660.
Texte intégralRésumé :
碩士朝陽科技大學
應用化學系碩士班
95
Abstract Among 11 local Baccillus spp. , the isolate 74501 with the highest yield of iturin A was chosen as the target of this study. The isolate 74501 was identified as Bacillus amyloliqufaciens(Ba-74501) by Biolog identification system. Results showed that after cultured in PSB medium for 6 days, and further assayed by HPLC, the isolate Ba-74501 was found to have at least 13 metabolic compounds. In vitro antifungal tests against Rhizoctonia solani with 13 compounds was performed. It was observed that compound 9 exhibited antifungal activity. Furthermore, TLC and ninhydrin colorization analysis confirmed that compound 9 was in absence of free amino group. The LC Q-TOF MS/MS analysis demonstrated that the molecular weight of compound 9 was 1042 m/z and proven to be iturin A2, Results revealed that isolate Ba-74501 also contained other antibiotic substances such as surfactin and fengycin.
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chang, sandy, et 張瓅心. « Synthesis, Identification, and Opto-electronic Property of Pyrene Derivative Isomers for Organic Light Emitting Diode Material ». Thesis, 2010. http://ndltd.ncl.edu.tw/handle/11521271929238805601.
Texte intégralRésumé :
碩士中原大學
化學研究所
98
In this study, pyrene was used to manufacture the blue light guest emitter for organic light emitting diode (OLED) elements. Bromine was first reacted with pyrene to form its 1,6- and 1,8-isomer. Then, different aromatic groups to increase its molecular volume, molecular weight, and molecular steric hindrance that can reduce the accumulation of molecules and decrease the interaction between molecules in a heavily doped material substituted bromine in the pyrene molecule. The blue OLEDs synthesized in this study are N1,N1,N6,N6-tetrakis(3,4-dimethylphenyl) pyrene-1,6- diamine (symboled as D1-1,6),N1,N1,N6,N6-tetrakis(3,4-dimethylphenyl)pyrene-1,8- diamine (symboled as D1-1,8), (N1,N6-di(naphthalenelyl)-N1,N6-diphenyl 1,6-diamine (symboled as D2-1,6), and N1,N8-di(naphthalenelyl)-N1,N8- diphenyl pyrene-1,8- diamine (symboled as D2-1,8). The 1,6- and 1,8-pyrene derivative isomers can be separated by their different properties of solubility and sublimation. High-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR), and mass spectrometry (MS) were used for monitoring the synthesis and identifying the structure of pyrene derivative isomers. The fluorescence property and the thermal stability with the melting point (Tm) and the degradation point (Td) of these blue light emitting materials were also studied in this work. Isomers of D1-1,6 and D1-1,8 and isomers of D2-1,6 and D2-1,8 were fabricated individually to make different types of blue light emitting thin film elements by the process of thermal evaporation and deposition, then, they were tested at the luminance of 5000 cd cm-2. With the same guest light emitting material and the same volume percentage of dopant (4%), the current efficiency of the four blue light emitting materials D1-1,6, D1-1,8, D2-1,6, and D2-1,8 is 7.5 cd A-1, 7.7 cd A-1, 8.1 cd A-1and 8.5 cd A-1, respectively. Because the molecular structures of 1,8-isomers are asymmetry and their steric hindrance is stronger, the light emitting efficiency of 1,8-isomers is better than that of the 1,6-isomers. In addition, the steric hindramce between the molecules of D2 compounds is stronger than that of D1 compounds so that the light emitting efficiency of D2 compounds is better than that of D1 compounds. Although the luminescent color of the fabricated elements from the four pyrene derivative isomers cannot reach a deep blue color, they are still valuable in the production of mono-chromatic OLED products.
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Ku, Min-Yen, et 古旻諺. « Hemicarceplex Formation Allows Ready Identification of the Isomers of the Metallofullerene Sc3N@C80 Using 1H and 13C NMR Spectroscopy ». Thesis, 2017. http://ndltd.ncl.edu.tw/handle/84045054381687127612.
Texte intégralRésumé :
博士國立臺灣大學
化學研究所
105
A cyclotriveratrylene-based molecular cage forms hemicarceplexes that significantly increase the solubility of commercially available Sc3N@C80 in CDCl3. When incarcerated within the molecular cage, the two structural isomers of this metallofullerene, Sc3N@D5h-C80 and Sc3N@Ih-C80, displayed characteristic signals in both 1H and 13C NMR spectra, allowing direct identification of each isomer without the need to enrich the sample with 13C atoms.
Chapitres de livres sur le sujet "Isomer identification"
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Harvey, David J. « Use of Ion Mobility for the Structural Identification of Glycans ». Dans Glycoprotein Analysis, 163–219. Royal Society of Chemistry, 2024. http://dx.doi.org/10.1039/9781839166433-00163.
Texte intégralRésumé :
This chapter describes the uses of ion mobility (IM) for the structural identification of carbohydrates and glycoconjugates. Topics covered are instrumentation, use of ion mobility for extracting glycan ions from mixtures, resolution of isomers, kinetic studies and applications. Recently introduced high-resolution instruments and their ability to separate carbohydrates by shape have revealed that many of these compounds exist in multiple forms (anomers, conformers, etc.) in the vapour phase, thus complicating the usefulness of the technique for isomer separation. Nevertheless, ion mobility has introduced another dimension to carbohydrate analysis, mainly by its ability to separate many glycan ions from complex mixtures and to provide cross-section measurements that can be used as an additional physical property to aid compound identification.
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BAUER, R. W., J. A. BECKER, E. A. HENRY et K. E. SALE. « SPECTROMETRY FOR SPIN AND SHAPE ISOMER IDENTIFICATION ». Dans Gamma-Ray Lasers, 637–50. Elsevier, 1988. http://dx.doi.org/10.1016/b978-0-08-037015-6.50004-3.
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E. Olajide, Orobola, Kimberly Y. Kartowikromo et Ahmed M. Hamid. « Ion Mobility Mass Spectrometry : Instrumentation and Applications ». Dans Mass Spectrometry - Recent Advances and Key Aspects [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.1002767.
Texte intégralRésumé :
The integration of ion mobility spectrometry with mass spectrometry (as an IM-MS hybrid instrument) provides additional analytical separation and identification capabilities that have greatly advanced various fields, including biomedical, pharmaceutical, and forensic sciences. In this chapter, a comprehensive exploration of various IMS instrumentation platforms is discussed, including Drift tube (DTIMS), Traveling wave (TWIMS), Trapped (TIMS), Field asymmetric waveform (FAIMS), and Differential mobility analyzer (DMA). Their respective advantages and limitations are evaluated in the context of distinct applications, including isomer separation, signal filtering to increase signal-to-noise ratio, and collision cross section (CCS) measurements in targeted and untargeted omics-based workflows. The scanning rate compatibility between various IMS devices and different mass analyzers resulted in various IM-MS hyphenation platforms. Higher sensitivity and selectivity are further achieved with the introduction of tandem IMS such as TIMS-TIMS-MS. IMS separations occur in the millisecond range and can therefore be easily incorporated into the liquid chromatography-mass spectrometry workflows and coupled with ambient ionization MS for metabolomics, lipidomic, proteomics, etc. The emergence of high-resolution IMS instruments such as Cyclic Ion Mobility Spectrometry (cIMS) and Structures for lossless ion manipulations (SLIM) is also discussed for the improvement of separation of isomers and increased predictive accuracy of CCS by machine learning models.
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Reichelt, Katharina V., Susanne Paetz, Karen M. Swanepoel, Jakob P. Ley et Gerhard E. Krammer. « Identification of a Sweet Taste Enhancing Vanillin Isomer from Mondia whitei via Sensory-Guided Analysis ». Dans Flavour Science, 573–76. Elsevier, 2014. http://dx.doi.org/10.1016/b978-0-12-398549-1.00105-7.
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Thurman, E. Michael. « Analysis of terpenes in hemp (Cannabis sativa) by gas chromatography/mass spectrometry : Isomer identification analysis ». Dans Analysis of Cannabis, 197–233. Elsevier, 2020. http://dx.doi.org/10.1016/bs.coac.2020.04.013.
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Puchowicz, Dorota, et Malgorzata Cieslak. « Raman Spectroscopy in the Analysis of Textile Structures ». Dans Recent Developments in Atomic Force Microscopy and Raman Spectroscopy for Materials Characterization [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.99731.
Texte intégralRésumé :
Raman spectroscopy as a non-destructive technique is very often used to analyze a historic or forensic material. It is also a very valuable method of testing textile materials, especially modified and functionalized. In the case of textiles, the advantages of this technique is the compatibility inter alia with FTIR, which is helpful in natural fibers identification or to distinguish between isomers and conformers of synthetic fibers. The work shows the possibility of special application of the Raman spectroscopy to the characterization of textile materials after modification and functionalization with nanoparticles. A functionalized textile structure with a metallic surface can provide a good basis for analytical studies using surface enhanced Raman spectroscopy as it was presented on the example of wool, cotton and aramid fibers.
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Claeys, M., Q. M. Li, H. Van Den Heuvel et L. Dillen. « Mass spectrometric studies on flavonoid glycosides ». Dans Applications of Modern Mass Spectrometry in Plant Science Research, 182–94. Oxford University PressOxford, 1996. http://dx.doi.org/10.1093/oso/9780198549659.003.0012.
Texte intégralRésumé :
Abstract Mass spectrometric methods based on the combined use of fast atom bombardment (FAB), collisionally-induced dissociation (CID) of positive ions, and tandem mass spectrometric techniques have been developed for the structural characterization of flavonoid glycosides containing aglycone moieties of the flavone or flavonol type. With respect to the characterization of flavonoid 0- glycosides, mass spectrometric methods involving low-energy CID yield information on: (1) the carbohydrate sequence; (ii) the aglycone moiety; and (iii) the glycosylation position. The characterization offlavonoid C-glycosides is addressed by high-energy CID, which enables differentiation between isomeric mono-6-C- and 8-C-glycosides, and isomeric di-6,8-C-glycosides. The structural elucidation offlavone O,C-diglycosides is accomplished by resorting to lowand high-energy CID; low-energy CID allows the determination of the type of the terminal O-linked carbohydrate residue, whereas high-energy CID enables identification of the type and the linkage position of the C-linked carbohydrate.
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Das, Prasanta. « Continuous Scan and Repetitive Mode FT-IR Spectroscopy and Its Application in Isomeric Identification, Conformational Analysis and Photochemistry ». Dans Infrared Spectroscopy - Perspectives and Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106448.
Texte intégralRésumé :
This chapter intends to cover the instrumentation of gas phase Fourier transform infrared spectroscopy (FT-IR), its recent advancement, and applications. The major focus have been given to the principle and data acquisition scheme of the repetitive mode measurement method of FT-IR spectrometer. The application of this spectroscopy in the isomeric identification of the methylated polycyclic aromatic hydrocarbons (MPAHs) and the conformational analysis of diols have been discussed. Furthermore, the application of the repetitive measurement mode of FT-IR combined with the UV laser in monitoring the atmospherically relevant photochemical reactions has been covered. In conclusion, this chapter briefly summarizes the current applications and discusses future applications of this technique in following drug degradation.
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Khoo, Kay-Hooi. « O-GalNAc Glycomics by LC–MS/MS ». Dans Glycoprotein Analysis, 279–99. Royal Society of Chemistry, 2024. http://dx.doi.org/10.1039/9781839166433-00279.
Texte intégralRésumé :
Mass spectrometry (MS) analysis of O-GalNAc glycans faces common glycomic challenges and presents unique considerations. Among the structural problems is the need to define the respective glycan chains and glycotopes on either the 6- or 3-arm of a branched core or those of an internal Gal attached to the reducing-end GalNAc. When considered together with the different positions of sialylation, fucosylation, and sulfation, the extent of isomeric variations can be too overwhelming to be resolved by any single analytical technique at the level of sensitivity and throughput demanded by current glycomics. Offline matrix-assisted laser desorption/ionization (MALDI)-based MS analysis is rather straightforward but ultimately limited by the quantitative identification of the isomeric constituents, particularly those of low abundance. Coupling to online liquid chromatography, either on a porous graphitized carbon column or on a reverse-phase C18 column for native and permethylated glycans, respectively, together with an MS2-product-dependent MS3 data acquisition workflow significantly increases the analytical depth. A good knowledge of the fragmentation pattern and diagnostic ions produced by different MS modes is indispensable to unambiguous structural assignments before any database-dependent, software-enabled data analysis can be routinely and reliably used. These technical aspects are highlighted and discussed at length here.
Actes de conférences sur le sujet "Isomer identification"
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Wei, Na, Enada Archibold, Grace Jairo et Heather Kuiper. « Development of a method for separation of geometric isomers of alpha-linolenic acid in human plasma by silver Ion HPLC and GC-NCI-MS ». Dans 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/fvyw5862.
Texte intégralRésumé :
Alpha-linolenic acid (ALA), an omega-3 fatty acid essential for humans, must be supplied by diet, mainly from plants. It's a precursor of omega-3 long-chain fatty acids, eicosapentaenoic and docosahexaenoic acids which are essential for human cardiovascular health. ALA consumption may also reduce the risk of heart disease. The geometric isomers of ALA in humans are derived from consumption of industrially produced partially hydrogenated and deodorized vegetable oils. The presence of trans-isomers of ALA in humans may affect the levels of regular ALA, potentially impacting the beneficial effects of ALA. Some studies have reported geometric isomers of ALA in human milk and serum but demonstrate incomplete chromatographic separation. The objective of this work is to develop a method to separate geometric isomers of ALA in human plasma using silver ion high-performance liquid chromatography (Ag-HPLC) and detect them using gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI-MS). Sample preparation involves acidic and alkaline hydrolysis of samples, followed by extraction of free fatty acids with hexane. Ag-HPLC is then employed for isomer separation, HPLC fractions containing each isomer are collected, and finally the samples are analyzed by GC-NCI-MS. Preliminary data shows all eight geometric isomers of ALA (n-3t6t9t, n-3t6t9c, n-3c6t9t, n-3t6c9t, n-3t6c9c, n-3c6t9c, n-3c6c9t, and n-3c6c9c) in plasma can be separated using this approach. Ag-HPLC separation of ALA isomers in human plasma resulted in the same elution times as the isomers in a standard mixture. The identities of the isomers were confirmed by comparing their retention times and mass-to-charge ratios with those of ALA isomer standards via GC-NCI-MS. This approach can potentially be used to investigate the distribution of ALA geometric isomers in human plasma. The full resolution of ALA geometric isomers can ensure accurate identification of these isomers in human plasma, which may aid in understanding their impact on human health.
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Isaac, Giorgis, Hernando Olivos et Robert Plumb. « Lipid separation and structural characterization using travelling wave cyclic ion mobility ». Dans 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/snxj7960.
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The analysis and structural characterization of lipids remain challenging due to the chemical structure diversity and isobaric nature. In recent years, liquid chromatography coupled to ion mobility-mass spectrometry (LC-IM-MS) for lipidomics has shown advantages in lipid identification. In particular, collision cross section (CCS) obtained from the IM measurements represents a physical property that can be used to enhance the confidence of lipid identification. Data were collected on a hybrid quadrupole cyclic IM (cIM) orthogonal acceleration time-of-flight instrument. It provides the option to perform either a single pass, or multiple passes until the desired resolution is achieved. MS and CID fragmentation data were obtained on precursor IM separated lipids followed by TOF mass measurement. Using the advanced travelling WAVE technology, a portion of the IMS separation can be selected and stored in a Pre-Array trap region. The stored ions can be re-injected to enable ion mobility analysis and by repeating this IMS to the “n” experiments can be performed. Ion mobility provides additional separation dimension that allows the separation of isobaric and isomeric compounds. The separation and structural characterization of different lipid classes using cIM is currently under study. Different lipid classes with positional isomer (Sn1/Sn2 vs Sn2/Sn1), different double bond positions, cis and trans isomers, glucosyl and galactosyl ceramide isomers, PIP and ganglioside isomers were investigated. Some of the isomers were baseline separated only after 1 pass (approximately at 65 IMS resolution) and others with 50 passes (approximately at 450 IMS resolution). In summary, cyclic IMS provides novel, scalable ion mobility resolution and the increased resolution is useful to resolve and separate isobaric and isomeric lipids species. Advanced modes of operation with ion activation followed by ion mobility separation offers new insights into lipid structural characterization.
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Bartlome, R., et M. W. Sigrist. « Laser-based isomer identification in the vapor phase ». Dans 2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference. IEEE, 2007. http://dx.doi.org/10.1109/cleoe-iqec.2007.4386405.
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Liu, Zhiqian, et Simone Rochfort. « Current challenges in phospholipid analysis in bovine milk ». Dans 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/taft4078.
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Phospholipids (PLs) are important components of milk fat globule membranes. They not only play the role of emulsifier ensuring the stability and homogeneity of the oil/water emulsion system of milk, but also have multiple beneficial functions vis-Ã -vis human health. PLs of milk are a complex family of polar lipids comprising several classes including PC, PE, SM, PS, PI, PA, PG and so on and each class contains a mixture of hundreds of molecular species differing in fatty acid (FA) composition and/or regio-position.Although PL quantification at the class level can be achieved by using NP-LC-ELSD and 31P-NMR, LC-MS (mainly HILIC-MS and RP-LC-MS) has become the prevalent analytical system for PL identification and quantification at the molecular species level. Unfortunately, combining LC separation with high-resolution MS detection is still insufficient to differentiate FA regio-isomers and double bond (DB) positional isomers, both being widely present in milk PLs. Additional techniques such as ozonolysis, UV-photodissociation and photochemical tagging in combination with LC-MS are needed for a complete structural characterization of PLs.Despite the recent progress, huge challenges remain to be overcome both in PL identification and quantification. This talk will discuss these in conjunction with the following aspects of bovine milk PLs. 1) pros and cons of different LC-MS methods in PL identification and quantification; 2) major PL class and species identified so far in bovine milk and 3) utility of Paterno-Buchi photochemical reaction in revealing regio-isomer and DB-positional isomers.
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FAHLANDER, C., R. HOISCHEN, D. RUDOLPH, M. HELLSTRÖM, S. PIETRI, ZS PODOLYÁK, P. H. REGAN et al. « ISOSPIN SYMMETRY AND PROTON DECAY : IDENTIFICATION OF THE 10+ ISOMER IN 54Ni ». Dans Proceedings of the 9th International Spring Seminar on Nuclear Physics. WORLD SCIENTIFIC, 2008. http://dx.doi.org/10.1142/9789812779038_0008.
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Kim, Jong-Suk, Eun-Mi Noh, Jeong-Mi Kim, Young-Rae Lee, Hyun Jo Youn, Sung Hoo Jung, Soo Mi Kim et Jinny Park. « Abstract 4218 : Guggulsterone controls isomer-specifically TPA-induced MMP-9 expressions of MCF-7 cells : Identification of the cooperative combination of guggulsterone isomers in inhibition of breast cancer invasiveness ». Dans Proceedings : AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011 ; Orlando, FL. American Association for Cancer Research, 2011. http://dx.doi.org/10.1158/1538-7445.am2011-4218.
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Wang, C. H., L. P. Gao et X. P. Wang. « Identification of Pentostain Isomers ». Dans 2015 Seventh International Conference on Measuring Technology and Mechatronics Automation (ICMTMA). IEEE, 2015. http://dx.doi.org/10.1109/icmtma.2015.136.
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Liu, Dianting, Zongying Ou, Guoqiang Wang, Shungang Hua et Tieming Su. « Face Recognition Using Hierarchical Isomap ». Dans 2007 IEEE Workshop on Automatic Identification Advanced Technologies. IEEE, 2007. http://dx.doi.org/10.1109/autoid.2007.380601.
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Genevey, J., J. A. Pinston, H. Faust, T. Friedrichs, M. Gross, F. Ibrahim, T. Larqué et S. Oberstedt. « Identification of μs isomers in fission products ». Dans EXOTIC NUCLEI AND ATOMIC MASSES. ASCE, 1998. http://dx.doi.org/10.1063/1.57273.
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Gu, Rui-jun, Wen-bo Xu et Bin Ye. « IMD-Isomap for Data Visualization and Classification ». Dans 2007 International Workshop on Anti-Counterfeiting, Security and Identification. IEEE, 2007. http://dx.doi.org/10.1109/iwasid.2007.373716.
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