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https://www.readbyqxmd.com/read/28328039/reduction-of-metal-adducts-in-oligonucleotide-mass-spectra-in-ion-pair-reversed-phase-chromatography-mass-spectrometry-analysis
#1
Robert E Birdsall, Martin Gilar, Henry Shion, Ying Qing Yu, Weibin Chen
RATIONALE: Electrospray ionization mass spectrometry (ESI-MS)-based techniques commonly used in oligonucleotide analyses are known to be sensitive to alkali metal adduct formation. Adducts directly impact the sensitivity of MS-based analyses as the available charge is distributed across the parent peak and adduct(s). The current study systematically evaluated common liquid chromatography (LC) components in LC/ESI-MS configurations used in oligonucleotide analysis to identify metal adduct contributions from LC instrumentation...
July 30, 2016: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28328032/product-ion-tandem-mass-spectrometric-differentiation-of-regioisomeric-side-chain-groups-in-cathinone-derivatives
#2
Younis Abiedalla, Jack DeRuiter, C Randall Clark
RATIONALE: Precursor materials are available to prepare aminoketone drugs containing regioisomeric propyl and isopropyl side-chain groups related to the drug alpha-pyrrovalerone (Flakka) and MDPV (3,4-methylenedioxypyrrovalerone). These compounds yield equivalent regioisomeric iminium cation base peaks in electron ionization mass spectrometry (EI-MS). METHODS: The propyl and isopropyl side-chain groups related to alpha-pyrrovalerone and MDPV were prepared and evaluated in EI-MS and tandem mass spectrometry (MS/MS) product ion experiments...
July 30, 2016: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28328026/alternative-mass-reference-standards-for-direct-analysis-in-real-time-mass-spectrometry
#3
Robert B Cody, A John Dane
RATIONALE: Mass spectra were acquired with the Direct Analysis in Real Time (DART®) ion source for an amine-terminated polyether used as positive-ion mass reference standards and for several fluorinated materials commonly used as negative-ion reference standards for mass spectrometry. METHODS: A commercial time-of-flight mass spectrometer equipped with a DART ion source was used for all measurements. Mass reference standards deposited onto the sealed end of a glass melting point tube were suspended in the DART gas stream for analysis...
May 30, 2016: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28328025/calibration-procedure-for-secular-frequency-scanning-in-ion-trap-mass-spectrometers
#4
Dalton T Snyder, Christopher J Pulliam, R Graham Cooks
RATIONALE: Mass spectra can be recorded using ion traps by scanning the frequency of an alternating current (ac) signal that corresponds to the secular frequency of a trapped ion. There is a considerable simplification in the instrumentation needed to perform such a scan compared with conventional scans of the radiofrequency (rf) amplitude. However, mass calibration is difficult. An algorithm that can be used to achieve mass calibration is investigated and the factors that affect ion mass assignments are discussed...
May 30, 2016: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28328019/dopant-assisted-direct-analysis-in-real-time-mass-spectrometry-with-argon-gas
#5
Robert B Cody, A John Dane
RATIONALE: Dopants used with Atmospheric Pressure Photoionization (APPI) were examined with the Direct Analysis in Real Time (DART(®) ) ion source operated with argon gas. Charge-exchange and proton transfer reactions were observed by adding toluene, anisole, chlorobenzene and acetone to the DART gas stream, complementing the information obtained by helium DART. METHODS: Mass spectra were acquired with a time-of-flight mass spectrometer equipped with a DART ion source operated with argon gas...
May 30, 2016: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28328018/abundance-correction-for-mass-discrimination-effects-in-polymer-mass-spectra
#6
Martin S Engler, Sarah Crotty, Markus J Barthel, Christian Pietsch, Ulrich S Schubert, Sebastian Böcker
RATIONALE: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is frequently used to analyze homo- and copolymers, i.e. for computing copolymer fingerprints. However, the oligomer abundances are influenced by mass discrimination, i.e. mass- and composition-dependent ionization. We have developed a computational method to correct the abundance bias caused by the mass discrimination. METHODS: MALDI-TOFMS in combination with computational methods was used to investigate three random copolymers with different ratios of styrene and isoprene...
May 30, 2016: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28327092/metax-a-flexible-and-comprehensive-software-for-processing-metabolomics-data
#7
Bo Wen, Zhanlong Mei, Chunwei Zeng, Siqi Liu
BACKGROUND: Non-targeted metabolomics based on mass spectrometry enables high-throughput profiling of the metabolites in a biological sample. The large amount of data generated from mass spectrometry requires intensive computational processing for annotation of mass spectra and identification of metabolites. Computational analysis tools that are fully integrated with multiple functions and are easily operated by users who lack extensive knowledge in programing are needed in this research field...
March 21, 2017: BMC Bioinformatics
https://www.readbyqxmd.com/read/28323431/au38-sph-24-au38-protected-with-aromatic-thiolate-ligands
#8
Milan Rambukwella, Shayna Burrage, Marie Neubrander, Oscar Baseggio, Edoardo Aprà, Mauro Stener, Alessandro Fortunelli, Amala Dass
Au38(SR)24 is one of the most extensively investigated gold nanomolecules along with Au25(SR)18 and Au144(SR)60. However, so far it has only been prepared using aliphatic-like ligands, where R = -SC6H13, -SC12H25 and -SCH2CH2Ph. Au38(SCH2CH2Ph)24 when reacted with HSPh undergoes core-size conversion to Au36(SPh)24, and existing literature suggests that Au38(SPh)24 cannot be synthesized. Here, contrary to prevailing knowledge, we demonstrate that Au38(SPh)24 can be prepared if the ligand exchanged conditions are optimized, under delicate conditions, without any formation of Au36(SPh)24...
March 21, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28322214/optical-signatures-of-parity-anomaly-in-a-gapped-graphene-like-system
#9
C X Zhang, X G Qiu
Parity anomaly refers to the violation of coordinate reflection symmetry induced by the quantum fluctuations. It is proposed to exist in a graphene-like system with a finite bare mass for Dirac fermions, and manifests itself as a parity- violating quantum correction to the current of each species of fermions. Coulomb interaction greatly increases the fermion mass, and produces various types of excitons. Of particular interest is the ρ-exciton, which is directly connected to parity anomaly and can be generated by absorbing a specific photon...
March 21, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28321994/detection-and-imaging-of-chrome-yellow-lead-chromate-in-latent-prints-solid-residues-and-minerals-by-laser-desorption-ionization-mass-spectrometry-ldi-ms
#10
Zhaoyu Zheng, Julius Pavlov, Athula B Attygalle
In the past, Chrome Yellow (lead chromate, PbCrO4 ), a bright orange-red substance, has been widely used as an inorganic pigment in the production of paints, coatings, and plastics. Herein, we demonstrate that laser desorption/ionization mass spectrometry (LDI-MS) is a powerful tool for the detection of lead chromate in solid residues. In fact, lead chromate in trace amounts is easily detectable by LDI-MS even from residues left as latent prints. For example, a latent print obtained by stamping the exposed laterally cut surface of a pencil over 50 years old on an acetonitrile-moistened paper, was successfully imaged for both lead and chromate using a Synapt G2 HDMS mass spectrometer...
March 21, 2017: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/28321655/quantum-chemical-nmr-ft-ir-and-esi-ms-studies-of-complexes-of-colchicine-with-zn-ii
#11
Wojciech Jankowski, Joanna Kurek, Piotr Barczyński, Marcin Hoffmann
Colchicine is a tropolone alkaloid from Colchicinum autumnale. It shows antifibrotic, antimitotic, and anti-inflammatory activities, and is used to treat gout and Mediterranean fever. In this work, complexes of colchicine with zinc(II) nitrate were synthesized and investigated using DFT, (1)H and (13)C NMR, FT IR, and ESI MS. The counterpoise-corrected and uncorrected interaction energies of these complexes were calculated. We also calculated their (1)H, (13)C NMR, and IR spectra and compared them with the corresponding experimentally obtained data...
April 2017: Journal of Molecular Modeling
https://www.readbyqxmd.com/read/28319797/non-enolisable-knoevenagel-condensate-appended-schiff-bases-metal-ii-complexes-spectral-characteristics-dna-binding-and-nuclease-activities
#12
Ammavasi Gubendran, Mookkandi Palsamy Kesavan, Srinivasan Ayyanaar, Liviu Mitu, Periyakaruppan Athappan, Jegathalaprathaban Rajesh
New Schiff base complexes [Cu(L(1))Cl] (1), [Ni(L(1))Cl] (2), [Zn(L(1))Cl] (3), and [Fe(L(2))H2OCl] (4) {L(1)=(4E)-3-(2-hydroxybenzylidene)-4-(2-hydroxyphenylimino)pentan-2-one, L(2)=2,2'-(1E,1'E)-(3-(2-hydroxybenzylidene)-pentane-2,4-diylidene)bis(azan-1-yl-1 idene)diphenol} have been synthesized and characterized by elemental analysis, UV-Vis, IR, FAB-mass, EPR, spectral studies and electrochemical studies, the ligands L(1) &L(2) were characterized by (1)H and (13)C NMR spectra. Complex 1 show a visible spectral d-d band near 600nm and display cyclic voltammetric quasireversible response for the Cu(II)/Cu(I) couple vs Ag/AgCl in DMSO...
March 16, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28319390/qualitative-behavior-of-the-low-frequency-vibrational-dynamics-of-microtubules-and-the-surrounding-water
#13
Jeremy M Moix, James E Parker, Ibtissam Echchgadda
The dynamics of the low-frequency vibrational modes of microtubules play a key role in many theoretical models regarding their biological function. We analyze these dynamics through large scale, classical molecular dynamics simulations of a microtubule composed of 42 tubulin heterodimers to provide insights into the qualitative nature of the vibrational energy absorption and dissipation mechanisms. The computed microtubule absorption spectra and vibrational density of states in the terahertz regime are presented, along with an analysis of the vibrational dephasing rates of the tubulin monomer center of mass dynamics, which are shown to be overdamped...
March 20, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28319298/diversity-in-gold-finger-structure-elucidated-by-traveling-wave-ion-mobility-mass-spectrometry
#14
Zhifeng Du, Raphael E F de Paiva, Kristina Nelson, Nicholas P Farrell
Traveling wave ion mobility (TWIM) mass spectrometry (MS) is a powerful method for the structural and conformational analysis of proteins and peptides, enabling the differentiation of isomeric peptides (or proteins) that have the same sequence but are modified at different residues. In this study, the TWIM-MS technique was used to separate isomeric Au(I) metallopeptide ions that were formed by Zn(II) displacement from the parent zinc fingers (ZFs). The synthetic gold finger peptides were derived from the C-terminus of the HIV nucleocapsid p7 protein (NCp7-F2) and finger 3 of the Sp1 transcription factor (Sp1-F3)...
March 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28316657/comprehensive-identification-of-sphingolipid-species-by-in-silico-retention-time-and-tandem-mass-spectral-library
#15
Hiroshi Tsugawa, Kazutaka Ikeda, Wataru Tanaka, Yuya Senoo, Makoto Arita, Masanori Arita
BACKGROUND: Liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) is used for comprehensive metabolome and lipidome analyses. Compound identification relies on similarity matching of the retention time (RT), precursor m/z, isotopic ratio, and MS/MS spectrum with reference compounds. For sphingolipids, however, little information on the RT and MS/MS references is available. RESULTS: Negative-ion ESI-MS/MS is a useful method for the structural characterization of sphingolipids...
2017: Journal of Cheminformatics
https://www.readbyqxmd.com/read/28302396/supercritical-antisolvent-co-precipitation-of-rifampicin-and-ethyl-cellulose
#16
Rania Djerafi, Andri Swanepoel, Christelle Crampon, Lonji Kalombo, Philip Labuschagne, Elisabeth Badens, Yasmine Masmoudi
Rifampicin-loaded submicron-sized particles were prepared through supercritical anti-solvent process using ethyl cellulose as polymeric encapsulating excipient. Ethyl acetate and a mixture of ethyl acetate/dimethyl sulfoxide (70/30 and 85/15) were used as solvents for both drug and polymeric excipient. When ethyl acetate was used, rifampicin was crystallized separately without being embedded within the ethyl cellulose matrix while by using the ethyl acetate/dimethyl sulfoxide mixture, reduced crystallinity of the active ingredient was observed and a simultaneous precipitation of ethyl cellulose and drug was achieved...
March 14, 2017: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28301162/determination-of-cell-doubling-times-from-the-return-on-investment-time-of-photosynthetic-vesicles-based-on-atomic-detail-structural-models
#17
Andrew Hitchcock, C Neil Hunter, Melih Sener
Cell doubling times of the purple bacterium Rhodobacter sphaeroides during photosynthetic growth are determined experimentally and computationally as a function of illumination. For this purpose, energy conversion processes in an intracytoplasmic membrane vesicle, the chromatophore, are described based on an atomic detail structural model. The cell doubling time and its illumination dependence are computed in terms of the return-on-investment (ROI) time of the chromatophore, determined computationally from the ATP production rate, and the mass ratio of chromatophores in the cell, determined experimentally from whole cell absorbance spectra...
March 16, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28301145/photodissociation-electronic-spectra-of-cold-protonated-quinoline-and-isoquinoline-in-the-gas-phase
#18
Géraldine Féraud, Luis Domenianni, Ernesto Marceca, Claude Dedonder-Lardeux, Christophe Jouvet
Photofragmentation electronic spectra of isolated single-isomeric N-protonated quinoline (quinolinium) and isoquinoline (isoquinolinium) ions have been measured at a temperature of ∼40 K using a mass-selective, 10 cm(-1) spectral resolution, photodissociation spectrometer. Additionally, ab-initio adiabatic transition energies calculated using the RI-ADC(2) method have been employed to assist in the assignment of the spectra. Three electronic transitions having ππ* character were clearly evidenced for both protonated ions within the UV and deep-UV spectral ranges...
March 16, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28299935/the-effect-of-structural-heterogeneity-in-chemical-composition-on-online-single-particle-mass-spectrometry-analysis-of-sea-spray-aerosol-particles
#19
Camille M Sultana, Douglas B Collins, Kimberly Ann Prather
Knowledge of the surface composition of sea spray aerosols (SSA) is critical for understanding and predicting climate-relevant impacts. Offline microscopy and spectroscopy studies have shown dry supermicron SSA tend to be spatially heterogeneous particles with sodium and chloride rich cores surrounded by organic enriched surface layers containing minor inorganic seawater components such as magnesium and calcium. At the same time, single particle mass spectrometry reveals several different mass spectral ion patterns, suggesting that there may be a number of chemically distinct particle types...
March 16, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28299859/analysis-of-maldi-q-tof-cid-spectra-of-simple-precursor-ions-and-isobaric-oligosaccharide-ion-mixtures-based-on-product-ion-intensities-and-pattern-recognition
#20
Marko Jovanović, Richard Tyldesley-Worster
RATIONALE: Qualitative data analysis of glycomic MS/MS data based on m/z values of product ions alone is widely used, and often sufficient for analysis of single analytes. However, most complex glycomic mixtures contain multiple isobaric oligosaccharides, in which case this approach is often limited. Here we show how ion intensity information can be used in order to enhance MS/MS data analysis, and extract both qualitative and semiquantitative information from complex glycomic MS/MS datasets...
March 15, 2017: Rapid Communications in Mass Spectrometry: RCM
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