Contributions to the Interpretation of Mass Spectrum of Tetraethoxysilane (TEOS). III. Accurate mass and M+1, M+2 isotopic effect measurements

2020 ◽  
Vol 71 (2) ◽  
pp. 209-217
Author(s):  
Virgil Badescu
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrum ◽  
High Resolution ◽  
Sol Gel ◽  
Isotopic Effect ◽  
Sol Gel Process ◽  
Primary Fragmentation ◽  
Fragmentation Reactions ◽  
Primary Ions ◽  
Isotopic Effects

The aim of this article in continuation of Parts I [1] and II [2] is the interpretation of the TEOS mass spectrum as a precursor in the sol-gel process. In Part I [1] the primary fragmentation ions at masses 207, 193, 179 and 163 were obtained experimentally by B/E linked scan by radical induced fragmentation reactions. In Part II [2] eliminations of neutral fragments from the primary ions and the obtained ions by consecutive elimination reactions were evidenced experimentally by the B/E and B/E(1-E)1/2 linked scans. In this third and final Part of interpretation of the TEOS mass spectrum, the separation of ions by mass spectrometry at high resolutions of 5000 and 6600, relative to standard resolution 1000, and measurements of the M+1 and M+2 isotopic effects at the resolution of 5000 are presented. The separation of the ions with nominal mass 105 at high resolution is detailed.

scholarly journals Contributions to the Interpretation of Mass Spectrum of Hexaethoxydisiloxane Linked scans and M+1, M+2 isotopic effects

2019 ◽  
Vol 70 (8) ◽  
pp. 2934-2939
Author(s):  
Virgil Badescu
Keyword(s):  
Mass Spectrum ◽  
Ionization Chamber ◽  
Quantum Calculations ◽  
Electronic Impact ◽  
Primary Fragmentation ◽  
Fragmentation Reactions ◽  
The Masses ◽  
Double Focusing ◽  
Primary Ions ◽  
Isotopic Effects

The aim of this article is the study of the fragmentation reactions of hexaethoxydisiloxane initiated by electronic impact in the ionization chamber of a double focusing mass spectrometer. The initiation center of fragmentation reactions is established by quantum calculations. The daughter ions of hexaethoxydisiloxane molecular ion are obtained by linked scan B/E. The primary fragmentation ions with the masses 341, 297, 296 and 269 were obtained experimentally by B/E linked scan by radical induced fragmentation reactions. The eliminations of neutral fragments such as hydrogen, acetaldehyde, ethylene and water from the primary ions and the obtained ions by consecutive elimination reactions were emphasized experimentally by the B/E(1-E)1/2 linked scan by charge induced reactions.

scholarly journals Contributions to the Interpretation of Mass Spectrum of Octaethoxycyclotetrasiloxane: Linked Scansand Isotopic Effects

Proceedings ◽  
2019 ◽  
Vol 29 (1) ◽  
pp. 103
Author(s):  
Virgil Badescu
Keyword(s):  
Mass Spectrum ◽  
Mass Spectrometer ◽  
Ionization Chamber ◽  
Electronic Impact ◽  
Fragmentation Reactions ◽  
Double Focusing ◽  
Isotopic Effects

The aim of this article is the study of the fragmentation reactions of octaethoxycyclotetrasiloxane (CTET) initiated by electronic impact in the ionization chamber of a double focusing mass spectrometer. [...]

scholarly journals Lipidomics of Environmental Microbial Communities. I: Visualization of Component Distributions Using Untargeted Analysis of High-Resolution Mass Spectrometry Data

2021 ◽  
Vol 12 ◽  
Author(s):  
Nicole J. Bale ◽  
Su Ding ◽  
Ellen C. Hopmans ◽  
Milou G. I. Arts ◽  
Laura Villanueva ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Mass Spectrum ◽  
High Resolution ◽  
Microbial Communities ◽  
Water Column ◽  
High Resolution Mass Spectrometry ◽  
Untargeted Analysis ◽  
High Resolution Mass ◽  
Resolution Mass

Lipids, as one of the main building blocks of cells, can provide valuable information on microorganisms in the environment. Traditionally, gas or liquid chromatography coupled to mass spectrometry (MS) has been used to analyze environmental lipids. The resulting spectra were then processed through individual peak identification and comparison with previously published mass spectra. Here, we present an untargeted analysis of MS1 spectral data generated by ultra-high-pressure liquid chromatography coupled with high-resolution mass spectrometry of environmental microbial communities. Rather than attempting to relate each mass spectrum to a specific compound, we have treated each mass spectrum as a component, which can be clustered together with other components based on similarity in their abundance depth profiles through the water column. We present this untargeted data visualization method on lipids of suspended particles from the water column of the Black Sea, which included >14,000 components. These components form clusters that correspond with distinct microbial communities driven by the highly stratified water column. The clusters include both known and unknown compounds, predominantly lipids, demonstrating the value of this rapid approach to visualize component distributions and identify novel lipid biomarkers.

scholarly journals Magnetically Separable Chiral Periodic Mesoporous Organosilica Nanoparticles

2020 ◽  
Vol 10 (17) ◽  
pp. 5960
Author(s):  
Suheir Omar ◽  
Raed Abu-Reziq
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Periodic Mesoporous Organosilica ◽  
X Ray ◽  
Mesoporous Organosilica ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
First Time

We describe, for the first time, a successful strategy for synthesizing chiral periodic mesoporous organosilica nanoparticles (PMO NPs). The chiral PMO nanoparticles were synthesized in a sol–gel process under mild conditions; their preparation was mediated by hydrolysis and condensation of chiral-bridged organo-alkoxysilane precursor compounds, (OR‘)3Si-R-Si(OR‘)3, in the presence of cetyltrimethylammonium bromide (CTAB) surfactant. The resulting nanoparticles were composed merely from a chiral- bridged organo-alkoxysilane monomer. These systems were prepared by applying different surfactants and ligands that finally afforded monodispersed chiral PMO NPs consisting of 100% bridged-organosilane precursor. In addition, the major advancement that was achieved here was, for the first time, success in preparing magnetic chiral PMO NPs. These nanoparticles were synthesized by the co-polymerization of 1,1′-((1R,2R)-1,2-diphenylethane-1,2-diyl)bis(3-(3-(triethoxysilyl) propyl) urea) chiral monomer by an oil in water (o/w) emulsion process, to afford magnetic chiral PMO NPs with magnetite NPs in their cores. The obtained materials were characterized with high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray (EDX) spectroscopy, powder X-ray diffraction (XRD), solid-state NMR analysis, circular dichroism (CD) analysis, and nitrogen sorption analysis (N2-BET).

High-resolution images of ultrafine LiCoO2 powders synthesized by a sol—gel process

1997 ◽  
Vol 68 (2) ◽  
pp. 519-523 ◽  
Author(s):  
G.T.K. Fey ◽  
K.S. Chen ◽  
B.J. Hwang ◽  
Y.L. Lin
Keyword(s):  
High Resolution ◽  
Sol Gel ◽  
Sol Gel Process ◽  
High Resolution Images

Structural and sequence effects in the fragmentation of protonated tripeptides containing tyrosine

2005 ◽  
Vol 83 (11) ◽  
pp. 1969-1977 ◽  
Author(s):  
Alex G Harrison
Keyword(s):  
Mass Spectrometry ◽  
Amide Bond ◽  
Collision Induced Dissociation ◽  
Relative Importance ◽  
Amino Acid Residues ◽  
Cyclic Dipeptide ◽  
Fragmentation Mechanisms ◽  
Sequence Effects ◽  
Primary Fragmentation ◽  
Fragmentation Reactions

The fragmentation reactions of a variety of protonated tripeptides containing tyrosine in the three possible positions have been studied by energy-resolved collision-induced dissociation mass spectrometry. The primary fragmentation reactions involve cleavage of the N-terminal and (or) C-terminal amide bond with the relative importance of the two cleavages depending strongly on the identity and position of the amino acid residues in the tripeptide. The results are interpreted in terms of the a1–y mechanism for cleavage of the N-terminal amide bond and the bx–yz mechanism for cleavage of the C-terminal amide bond and, indeed, provide support for these mechanisms. However, it appears likely that, for protonated H-Val-Tyr-Pro-OH, the neutral accompanying formation of the y1 (protonated proline) ion is a cyclic dipeptide (cyclo-Val-Tyr) rather than the oxazolone predicted by the bx–yz mechanism.Key words: tyrosine-containing peptides, fragmentation mechanisms, tandem mass spectrometry.

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