Gas Phase Ions
Mostrando 1-12 de 45 artigos, teses e dissertações.
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1. TÉCNICAS AVANÇADAS PARA A DIFERENCIAÇÃO DE ISÔMEROS POR ESPECTROMETRIA DE MASSAS
Mass spectrometry (MS) is a powerful and widespread technique but is inherently uncapable to differentiate species with same m/z ratio. For this reason, many classical approaches were developed based on differential fragmentation patterns in tandem MS. More recently, new techniques for isomer identification in MS were developed, and we highlight the photodis
Quím. Nova. Publicado em: 2020-09
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2. Structural Study of Phenolic Acids by Triple Quadrupole Mass Spectrometry with Electrospray Ionization in Negative Mode and H/D Isotopic Exchange
This work reports the theoretical and experimental study of fragmentation reactions in the gas phase of five phenolic acids using triple quadrupole mass spectrometry by electrospray ionization in negative ionic mode, as well as the isotope exchange experiments. MS/MS spectra were analyzed to suggest the fragmentation mechanisms, while theoretical calculation
J. Braz. Chem. Soc.. Publicado em: 2020-02
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3. Characterization and Comparative Analysis of Corrosion Resistance of 4 High Manganese Steels Models in Aqueous Solution of NaCl
The liquefied natural gas volumes that currently need to be stored and/or transported require engineering to consistently develop materials that combine high mechanical strength and low manufacturing costs. The present work brings the study of four models of high manganese steels (non-commercials), to demonstrate the feasibility of being used in the petroche
Mat. Res.. Publicado em: 09/12/2019
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4. Fragmentation Reactions of Rhodamine B and 6G as Revealed by High Accuracy Orbitrap Tandem Mass Spectrometry
Correct interpretation of mass spectra is essential to our understanding of the ion chemistry occurring in the gas phase inside mass spectrometers and for constructing a solid knowledge from which mass spectrometry (MS) data of novel molecules will be interpreted. Assignments of product ions leading to incorrect dissociation mechanisms can also be dangerous
J. Braz. Chem. Soc.. Publicado em: 2017-01
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5. Gas-Phase Nucleophilic Reactivity of Alkoxysilanes
A reatividade em fase gasosa das alcoxissilanas do tipo Me4-nSi(OEt)n (n = 1-3) foi investigada por ressonância ciclotrônica de íons por transformada de Fourier (FT-ICR) com o intuito de se caracterizar os mecanismos de ataque nucleofílico nesses importantes precursores de novos materiais. Nucleófilos como F-, MeO- e EtO- reagem rapidamente e de forma p
J. Braz. Chem. Soc.. Publicado em: 2013-02
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6. Atribuição absoluta e geral de isômeros constitucionais por espectrometria de massas: o caso das metilpiperidinas
An absolute method is described via mass spectrometry (MS) for the structural assignment of isomers within the class of methylpiperidines. The method explores both the unimolecular and bimolecular gas phase behavior of structurally diagnostic fragment ions (SDFI). For the methylpiperidnes, the isomeric 2-methyl, 3-methyl and 4-methyl 2-azabutadienyl cations
Química Nova. Publicado em: 2012
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7. Determinação de hormônios estrógenos e progestágenos em amostras ambientais por GC-MS
Due to the constant increase in population, the level of pollution on the planet has grown mainly in aquatic environments. Some of these contaminants present regulation but a fraction of these, called "emerging", besides being continuously released into the environment without any control, have no regulation. Sex hormones are part of these emerging contamina
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 2012
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8. Mobilidade ionica acoplada a espectrometria de massas : interferencia de parametros do drift gas na resolução de anilinas substituidas e determinação da mobilidade intrinsica de agregados de liquidos ionicos / Ion mobility mass spectrometry : interference of drift gas parameters on the resolution of substituted anilines and determination of intrinsic mobility of ionic liquids aggregates
Ion mobility spectrometry separates ions with different sizes or spacial conformations in gas phase according to the time they take to travel through a gas under the influence of an electrical field. Coupling this technique to mass spectrometry provides an extremely versatile tool, able to investigate molecular structure and separate complex samples, includi
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 24/02/2010
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9. Solvolysis reactions of cation +SiCl3: Experiment and Theory / Reações de solvólise em fase gasosa do cátion +SiCl3: experimento e teoria
Polyhalogenated silicenium ions, X3Si+ (X = F, Cl), are common fragment ions in the mass spectra of polyhalogenated silanes obtained by electron ionization. These ions are powerful electrophiles and are believed to play a role in plasma enhanced corrosion processes and plasma enhanced chemical vapour deposition processes. In this dissertation, we present som
Publicado em: 2010
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10. Gas-phase solvolysis type reactions of SiCl3+ cations
Gas-phase SiCl3+ ions undergo sequential solvolysis type reactions with water, methanol, ammonia, methylamine and propylene. Studies carried out in a Fourier Transform mass spectrometer reveal that these reactions are facile at 10-8 Torr and give rise to substituted chlorosilyl cations. Ab initio and DFT calculations reveal that these reactions proceed by ad
Química Nova. Publicado em: 2010
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11. Tropical peat as a versatile material for solid-phase extraction of pesticides from medicinal plant Cordia salicifolia
A turfa natural foi testada na extração em fase sólida de acefato, clorprofam, pirimicarbe, bifentrina, tetradifona e fosalona da planta medicinal Cordia salicifolia, utilizando cromatografia a gás acoplada a espectrometria de massas no modo de monitoramento de íons selecionados. Considerando que a legislação brasileira não estabelece limites máximo
Journal of the Brazilian Chemical Society. Publicado em: 2010
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12. Folatos, capacidade antioxidante e trans-2-nonenal em cerveja brasileira / Folate, antioxidant capacity and E-2-nonenal in Brazilian beer
In the present study methods were adapted and applied to quantify levels of folate, antioxidant capacity assessment and E-2-nonenal quantification in Brazilian beers. 5 brands of Pilsen, non-alcoholic and Malzbier beers were used, in can and amber bottle. For determination of folates (folic acid - FA, 10-methyl-folic acid - 10Methyl, 5-methyltetrahydrofolate
Publicado em: 2010