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Journal of Mass Spectrometry: JMS

R Pepin, C J Shaffer, F Tureček
We report diazirine photochemical tags that can be incorporated at peptide N-termini and in lysine residues using a simple solid-state alkylation procedure. The diazirine-tagged peptides are used for photochemical carbene formation at 355 nm and crosslinking of non-covalent peptide-peptide ion complexes in the gas-phase. The new tags allow one to control the charge sites in the complexes and use tandem mass spectrometry for gas-phase sequencing to localize the cross links.
June 20, 2017: Journal of Mass Spectrometry: JMS
H Zhang, A Bibi, H Lu, J Han, H Chen
It is of sustainable interest to improve the sensitivity and selectivity of the ionization process, especially for direct analysis of complex samples without matrix separation. Herein, four ambient ionization methods including desorption atmospheric pressure chemical ionization (DAPCI), heat-assisted desorption atmospheric pressure chemical ionization (heat-assisted DAPCI), microwave plasma torch (MPT), and internal extractive electrospray ionization (iEESI) were employed for comparative analysis of the navel orange tissue samples by mass spectrometry...
June 19, 2017: Journal of Mass Spectrometry: JMS
J Schätti, U Sezer, S Pedalino, J P Cotter, M Arndt, M Mayor, V Köhler
Amino acids are essential building blocks of life and fluorinated derivatives have gained interest in chemistry and medicine. Modern mass spectrometry has enabled the study of oligo- and polypeptides as isolated entities in the gas phase, but predominantly as singly or even multiply charged species. While laser desorption of neutral peptides into adiabatically expanding supersonic noble gas jets is possible, UV-VIS spectroscopy, electric or magnetic deflectometry as well as quantum interferometry would profit from the possibility to prepare thermally slow molecular beams...
June 12, 2017: Journal of Mass Spectrometry: JMS
M Bouza, J Fandino, N Bordel, R Pereiro, A Sanz-Medel
Pulsed glow discharge (PGD) coupled to time of flight mass spectrometry (TOFMS) has been investigated for volatile organic compounds (VOCs) identification and determination. Optimization of PGD operational conditions (chamber design, applied power, pressure and duty cycle) was performed using acetone and benzene as model compounds. During the different optimizations, molecular, fragment and elemental information were obtained when characteristic GD pulse regions were measured. An exploratory study for several VOCs (lineal hydrocarbons, oxygen-containing compounds and aromatic compounds) revealed the capability of the PGD to provide crucial information to elucidate structures (fragments), molecular ions or even proton affinity nature of the molecules; this last information is a consequence of the enriched proton environment generated along the afterglow region for the ionization chamber used...
June 12, 2017: Journal of Mass Spectrometry: JMS
C Schueuermann, P Bremer, P Silcock
No abstract text is available yet for this article.
June 9, 2017: Journal of Mass Spectrometry: JMS
E A da Silva-Junior, C R Paludo, D R Gouvea, M J Kato, N A J C Furtado, N P Lopes, R Vessecchi, M T Pupo
Piplartine, an alkaloid produced by plants in the genus Piper, displays promising anticancer activity. Understanding the gas-phase fragmentation of piplartine by electrospray ionization tandem mass spectrometry can be a useful tool to characterize biotransformed compounds produced by in vitro and in vivo metabolism studies. As part of our efforts to understand natural product fragmentation in electrospray ionization tandem mass spectrometry, the gas-phase fragmentation of piplartine and its two metabolites 3,4-dihydropiplartine and 8,9-dihydropiplartine, produced by the endophytic fungus Penicillium crustosum VR4 biotransformation were systematically investigated...
June 5, 2017: Journal of Mass Spectrometry: JMS
A H El-Khatib, Y He, D Esteban-Fernández, M W Linscheid
DOTA derivatives are applied in quantitative proteomics owing to their ability to react with different functional groups, to harbor lanthanoides and hence their compatibility with molecular and elemental mass spectrometry. The new DOTA derivatives, namely Ln-MeCAT-Click and Ln-DOTA-Dimedone, allow efficient thiol labeling and targeting sulfenation as an important post-translational modification, respectively. Quantitative applications require the investigation of fragmentation behavior of these reagents. Therefore, the fragmentation behavior of Ln-MeCAT-Click and Ln-DOTA-Dimedone was studied using collision-induced dissociation (CID), infrared multiphoton dissociation (IRMPD) and higher-energy collision dissociation (HCD) using different energy levels and the efficiency of reporter ion production was estimated...
June 2, 2017: Journal of Mass Spectrometry: JMS
N D Schmitt, J N Agar
Conformational change and modification of proteins are involved in many cellular functions. However, they can also have adverse effects that are implicated in numerous diseases. How structural change promotes disease is generally not well understood. This perspective illustrates how mass spectrometry (MS), followed by toxicological and epidemiological validation, can discover disease-relevant structural changes and therapeutic strategies. We (with our collaborators) set out to characterize the structural and toxic consequences of disease-associated mutations and post-translational modifications (PTMs) of the cytosolic antioxidant protein Cu/Zn-Superoxide dismutase (SOD1)...
May 30, 2017: Journal of Mass Spectrometry: JMS
U Duthaler, B Berger, S Erb, M Battegay, E Letang, S Gaugler, S Krähenbühl, M Haschke
For therapeutic drug monitoring (TDM) in remote settings, dried blood spots (DBS) are particularly advantageous, as blood sample collection and handling is uncomplicated. The aim of this study was to develop and validate an automated extraction method for the analysis of nevirapine, efavirenz, and lopinavir in DBS samples. Automated extraction was performed with methanol:water (70:30 v/v), using a DBS-MS 500 autosampler coupled to a LC-MS/MS system. The autosampler used digital images of each DBS to position the extraction head, sprayed 10 μL internal standard (IS) onto each DBS and extracted a 4 mm disk (Ø) from the centre of each spot by unilateral flow using 25 μl extraction solvent...
May 29, 2017: Journal of Mass Spectrometry: JMS
Yasuhiko Ohrui, Tomoki Nagoya, Naoko Kurimata, Manabu Sodeyama, Yasuo Seto
A field-portable gas chromatography-mass spectrometry (GC-MS) system (Hapsite ER) was evaluated for the detection of nonvolatile V-type nerve agents (VX and Russian VX (RVX)) in the vapor phase. The Hapsite ER system consists of a Tri-Bed concentrator gas sampler, a nonpolar low thermal-mass capillary gas chromatography column and a hydrophobic membrane-interfaced electron ionization quadrupole mass spectrometer evacuated by a non-evaporative getter pump. The GC-MS system was attached to a VX-G fluoridating conversion tube containing silver nitrate and potassium fluoride...
May 25, 2017: Journal of Mass Spectrometry: JMS
J K Prasain, L S Wilson, A Arabshahi, C Grubbs, S Barnes
The purpose of this study was to investigate the effect of radiation on the content of animal diet constituents using global metabolomics. Aqueous methanolic extracts of control and cobalt-60 irradiated NIH 7001 diets were comprehensively analyzed using nanoLC-MS/MS. Among the over two thousand ions revealed by XCMS followed by data preprocessing, 94 positive and 143 negative metabolite ions had greater than 1.5 fold changes and p-values <0.01. Use of Metaboanalyst statistical software demonstrated complete separation of the irradiated and non-radiated diets in unsupervised principal components analysis and supervised partial least squares discriminant analysis...
May 24, 2017: Journal of Mass Spectrometry: JMS
G Shankar, R M Borkar, S Udutha, L Guntuku, V G M Naidu, N Nagesh, R Srinivas
Regulatory agencies from all over the world have set up stringent guidelines with regard to drug degradation products due to their toxic effects or carcinogenicity. Lansoprazole, a proton-pump inhibitor, was subjected to forced degradation studies as per ICH guidelines Q1A (R2). The drug was found to degrade under acidic, basic, neutral hydrolysis and oxidative stress conditions, whereas it was found to be stable under thermal and photolytic conditions. The chromatographic separation of the drug and its degradation products were achieved on a Hiber Purospher, C18 (250 X 4...
May 20, 2017: Journal of Mass Spectrometry: JMS
Niclas Nikolai Stephanson, Patrick Signell, Anders Helander, Olof Beck
The influx of new psychoactive substances (NPS) has created a need for improved methods for drug testing in toxicology laboratories. The aim of this work was to design, validate and apply a multi-analyte liquid chromatography-high resolution mass spectrometry (LC-HRMS) method for screening of 148 target analytes belonging to the NPS class, plant alkaloids and new psychoactive therapeutic drugs. The analytical method used a five-fold dilution of urine with 9 deuterated internal standards and injection of 2 μL...
May 10, 2017: Journal of Mass Spectrometry: JMS
Marianne Engeser, Christian Mundt, Christoph Bauer, Stefan Grimme
Electron ionisation mass spectra of N-methylimidazolidin-4-one organocatalysts were studied by experimental and theoretical means. The molecular ions mostly undergo alpha cleavages of exocyclic substituents that leave the five-membered ring intact. The type of substituent strongly dominates the appearance of the spectra. Fragmentation cascades are corroborated by metastable ion mass spectra. Quantum Chemistry Electron Ionization Mass Spectra calculations correlate reasonably well with the experimental electron ionization spectra and reveal mechanistic details of fragmentation pathways...
May 8, 2017: Journal of Mass Spectrometry: JMS
Jean-Arthur Amalian, Abdelaziz Al Ouahabi, Gianni Cavallo, Niklas Felix König, Salomé Poyer, Jean-François Lutz, Laurence Charles
Following publication as an Accepted Article, this article was put on hold on 10(th) May 2017 to preserve the embargo status of a companion paper in an alternate publication.
May 8, 2017: Journal of Mass Spectrometry: JMS
Zhihui Yin, Changhai Sun, Hongzhuang Fang
This work aims to analyze the electrospray ionization multistage mass spectrometry (ESI-MS(n) ) fragmentation characteristics of hydroxycinnamic acids (HCAs) in negative ion mode. The geometric parameters, energies, natural bond orbitals and frontier orbitals of fragments were calculated by density functional theory (DFT) to investigate mass spectral fragmentation mechanisms. The results showed that proton transfer always occurred during fragmentation of HCAs; their quasi-molecular ions ([M-H](-) ) existed in more than one form and were mainly with the lowest energy...
May 8, 2017: Journal of Mass Spectrometry: JMS
David Rodriguez-Temporal, Daniel Perez-Risco, Eduardo A Struzka, Mireia Mas, Fernando Alcaide
Conventional identification of mycobacteria species is slow, laborious and has low discriminatory power. MALDI-TOF MS has proved highly effective for identifying conventional bacteria, and it may also be useful for identifying mycobacteria. The aim of this study was to evaluate and compare MALDI-TOF MS with currently recommended molecular methods for the identification of nontuberculous mycobacteria (NTM), applying Mycobacteria Libraries v3.0 (ML3.0) and v2.0 (ML2.0). A total of 240 clinical isolates of 41 NTM species grown on solid media were analysed: 132 isolates of slow-growing mycobacteria and 108 of rapid-growing mycobacteria...
May 8, 2017: Journal of Mass Spectrometry: JMS
Anu Teearu, Signe Vahur, Toomas Rodima, Koit Herodes, Werner Bonrath, Thomas Netscher, Sofja Tshepelevitsh, Aleksander Trummal, Märt Lõkov, Ivo Leito
Matrix-assisted laser desorption/ionization (MALDI) is a mass spectrometry (MS) ionization technique suitable for a wide variety of sample types including highly complex ones such as natural resinous materials. Coupled with Fourier transform ion cyclotron resonance (FT-ICR) mass analyzer, which provides mass spectra with high resolution and accuracy, the method gives a wealth of information about the composition of the sample. One of the key aspects in MALDI-MS is the right choice of matrix compound. We have previously demonstrated that 2,5-dihydroxybenzoic acid (DHB) is suitable for the positive ion mode analysis of resinous samples...
May 4, 2017: Journal of Mass Spectrometry: JMS
Lu Wang, Yali Wang, Yunfeng Chai, Yu Kang, Cuirong Sun, Su Zeng
A facile method based on electrospray mass spectrometry was established and validated for the differentiation of enantiomeric Tadalafil isomers without using chiral chromatographic separation. The enantiomers were coupled with a chiral selector to form diastereomeric complex ions. Nickel-Tadalafil complexes, [Ni(II) (Tadalafil)(L-Trp)-H](+) , produced a characteristic fragment ion at m/z 524 by loss of 1-methyl-1, 6-dihydropyrazine-2, 5-dione (MDD) via collision-induced dissociation (CID). The relative abundance of this fragment ion to the precursor contributed to differentiate Tadalafil enantiomers, and energy-resolved product-ion spectra were applied to determine molar composition of Tadalafil in the mixture (R, R and S, S) as well...
May 4, 2017: Journal of Mass Spectrometry: JMS
Sebastian Beck, Sabrina Trog, Sarah Knizia, Michael W Linscheid
1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) is a macrocycle that is able to complexate a large variety of metals. The stability of these metal complexes is generally very high. This has led to the use of these complexes in medical applications, e.g. magnetic resonance imaging. Here, we have investigated the fragmentation behavior of a number of DOTA-metal complexes under collision-induced dissociation (CID), infrared-multiphoton dissociation (IRMPD) and higher-energy collisional dissociation (HCD) activation conditions...
April 28, 2017: Journal of Mass Spectrometry: JMS
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