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Journal of Mass Spectrometry: JMS

Manikandan Muthu, Sechul Chun, Hui-Fen Wu, Mark W Duncan, Judy Gopal
The practice of laser desorption/ionization (LDI) mass spectrometry continues to evolve. In the most commonly adopted manifestation of LDI, matrix assisted laser desorption/ionization (MALDI), attention continues to be directed towards novel sample application strategies and modifications to the sample plate. Specifically, researchers continue to explore adaptations to the conventional, stainless steel sample plate that is the centerpiece of conventional LDI. Numerous variants of LDI-MS have been reported based on modifications of the plate surface, but none of these is widely adopted, either by end-users or instrument manufacturers...
March 13, 2018: Journal of Mass Spectrometry: JMS
Gabriela Petroselli, Marilina Raices, Lucas D Jungblut, Andrea G Pozzi, Rosa Erra-Balsells
In many amphibians, the granular glands can be grouped in special regions forming macroglands. This is the case of toads, characterized by the presence of a pair of parotoid macroglands, strategically located to give protection by poison release in case of attacks. The product secreted consists of a wide variety of chemical compounds including proteins, peptides, biogenic amines, toxic steroidal bufadienolides, various alkaloids, depending on the species. In this work, using Rhinella arenarum we have performed, for the first time, the MALDI-MS and MS/MS characterization of the components of the secretion used as crude material, just suspended in MeOH (or MeCN)...
March 10, 2018: Journal of Mass Spectrometry: JMS
V F Sardela, M E P Martucci, A L D de Araújo, E S Leal, D S Oliveira, G R Carneiro, K Deventer, P Van Eenoo, H M G Pereira, F R Aquino Neto
No abstract text is available yet for this article.
March 9, 2018: Journal of Mass Spectrometry: JMS
Tamar Shamai Yamin, Hagit Prihed, Avital Shifrovitch, Shai Dagan, Avi Weissberg
A novel analytical technique for the structural elucidation of compounds bearing a tertiary amine side chain via "in vial" instantaneous oxidation and liquid chromatography-mass spectrometry (LC-MS) was developed. A series of lidocaine homologues and benzimidazole derivatives with a major/single amine-representative base peak in both their EI-MS and ESI-MS/MS spectra were subjected to oxidation by a 0.1% solution of hydrogen peroxide )including several16 O/18 O exchange experiments(, followed by LC-ESI-MS/MS analysis...
March 9, 2018: Journal of Mass Spectrometry: JMS
Hong Zhang, Kai Yu, Na Li, Jing He, Hong You, Jie Jiang
Reactive intermediates play key roles for reaction mechanism elucidation. A suitable tool for identifying the key intermediates is crucial and highly desirable. In this study, surface desorption dielectric-barrier discharge ionization (Reactive SDDBDI) was developed for characterization of the reactive intermediates. In reactive SDDBDI, the plasma is doped with a reagent before the plasma ions are directed at a cover slip surface bearing another analyte. Different from SDDBDI, reactive SDDBDI can be used both as an ambient ionization source and as a means to produce reagent ions for ambient ion/molecule reactions...
March 9, 2018: Journal of Mass Spectrometry: JMS
Guiqin Wang, Yuling Zeng, Jifeng Xu, Wengui Liu
We report a new method for calibrating the current gain of 1013 Ω amplifiers in both positive and negative mode used in thermal ionisation mass spectrometry (TIMS). This method uses any isotopic standard or sample to calibrate the gain factor as long as it can produce a stable current signal. It is simpler and more flexible than that recommended by Thermo-Fisher (the manufacture of the TIMS). In these analyses, the gains of five 1013 Ω amplifiers were assessed. The precision of gain factors was better than 100 ppm (2 RSD) in a day, and the long term reproducibility was better than 300 ppm (2 RSD) within 2 - 8 months...
March 9, 2018: Journal of Mass Spectrometry: JMS
Arshad Mehmood, Benjamin G Janesko
A method is proposed to predict ions' collision cross-sectional area (CCS) from properties that are already evaluated in standard quantum chemistry software. Computed molecular isodensity surface areas recover the predictions of existing projection approximations. Computed solvent cavity areas give comparable accuracy. This provides a simplified workflow for assigning ion-mobility mass spectra.
March 5, 2018: Journal of Mass Spectrometry: JMS
Zhibin Yin, Le Hang, Rong Liu, Wei Hang, Benli Huang
A newly constructed laser desorption (532 nm, 5 ns) and laser postionization (266 nm, 5 ns) time-of-flight mass spectrometer (LD-LPI-TOFMS) has been applied for improving the detection sensitivity of elements in solid samples. This method affords to acquire the information of the elemental impurities in solid standards as well as limit of detection (LOD) down to 10-8 g/g for some elements. Neutral atoms of solids are generated by low-irradiance laser desorption (< 108 W/cm2 ), followed by high-irradiance laser postionization (~ 109 W/cm2 ) of the desorbed atoms, facilitating to decoupling the desorption and ionization processes in spatial and temporal domain...
March 5, 2018: Journal of Mass Spectrometry: JMS
Ana Paula Ferranti Peti, Gisele Aparecida Locachevic, Morgana Kelly Borges Prado, Luiz Alberto Beraldo Moraes, Lúcia Helena Faccioli
Multiple reaction monitoring (MRM) is one of the most powerful modes of analysis in liquid chromatographic tandem mass spectrometry (LC-MS/MS) for quantification of low-concentration metabolites in biological samples. The advances in mass spectrometry enabled the development of high-resolution multiple reaction monitoring (MRMHR ) and became suitable for the more specific analysis of target analytes. This is important for lipidomic studies and contributes in the medical and pharmaceutical fields, primarily in investigating alterations in cells or fluids relevant to various diseases...
March 1, 2018: Journal of Mass Spectrometry: JMS
Carlos A Valdez, Roald N Leif, Saphon Hok, Armando Alcaraz
Revision of the NIST library spectrum for the compound 5,5-diphenyl-1,3-dioxolan-4-one is presented. After the synthesis and characterization (by NMR and MS) of 5,5-diphenyl-1,3-dioxolan-4-one, it was found that its mass spectral data did not match the one found in the NIST database. Herein, we present a revised version of the spectrum corresponding to the material and a comparative analysis to the previously published data.
February 27, 2018: Journal of Mass Spectrometry: JMS
Mehmet Ali Tetik, Onur Sevindik, Hasim Kelebek, Serkan Selli
The principal purpose of the present work is to characterize the aroma, aroma-active, and anthocyanin profiles of Okuzgozu wines and to observe the effect of the pomace pressing technique on these parameters. A total of 58 and 59 volatile compounds were identified and quantified in free-run juice wine (FRW) and pressed pomace wine (PW). Alcohols were found as the most dominant group among aroma compounds followed by esters and acids. However, among all these compounds only 11 and 13 of them could be considered as key odorants in aromatic extracts of FRW and PW, respectively...
February 22, 2018: Journal of Mass Spectrometry: JMS
Lee Chuin Chen, Satoru Tsutsui, Tsubasa Naito, Satoshi Ninomiya, Kenzo Hiraoka
A new electrospray source design is introduced by having an extractor electrode placed at 1~2 mm behind the emitter tip. The extractor was integrated into the sprayer body as a single device. An insulating tube was used to isolate the emitter from the extractor and to deliver the sheath gas for the electrospray. The electric field strength at the emitter was primarily determined by the relative position and the potential between the needle and the extractor, therefore, the spraying condition was insusceptible to the change of sprayer position or orientation with respect to the ion sampling inlet...
February 17, 2018: Journal of Mass Spectrometry: JMS
Ines Starke, Andreas Koch, Stefan Kammer, Hans-Jürgen Holdt, Heiko Michael Möller
The complex formation of the following diazaperylene ligands (L) 1,12-diazaperylene 1, 1,1'-bisisoquinoline 2, 2,11-disubstituted 1,12-diazaperylenes (alkyl=methyl, ethyl, isopropyl, 3, 5, 7), 3,3'-disubstituted 1,1'-bisisoquinoline (alkyl=methyl, ethyl, isopropyl), 4, 6, 8 and with R = phenyl, 11 and with pyridine 12) and the 5,8-dimethoxy-substituted diazaperylene 9, 6,6'- dimethoxy-substituted bisisoquinoline 10 with AgBF4 was investigated. Collision-induced dissociation measurements were used to evaluate the relative stabilities of the ligands themselves and for the [1:1] + complexes as well as for the homoleptic and heteroleptic silver [1:2] + complexes in the gas phase...
February 16, 2018: Journal of Mass Spectrometry: JMS
Raju Bandu, Hyun Jeong Lee, Hyeong Min Lee, Tae Hyon Ha, Heon-Jeong Lee, Se Joo Kim, Kyooseob Ha, Kwang Pyo Kim
Liquid chromatography-mass spectrometry (LC-MS) method revealed the plasma metabolite profiles in major depressive disorder (MDD) patients treated with escitalopram (ECTP) (n=7). Depression severity was assessed according to the 17-item Hamilton Depression Rating Scale (HAMD-17). Metabolic profiles were derived from MDD subject blood samples collected after ECTP treatment. Blood plasma was separated and processed in order to effectively extract metabolites, which were then analyzed using LC-MS. We identified 19 metabolites and elucidated their structures using LC-tandem mass spectrometry (LC-MS/MS) combined with elemental compositions derived from accurate mass measurements...
February 15, 2018: Journal of Mass Spectrometry: JMS
Rafał Frański, Błażej Gierczyk, Maciej Zalas, Wojciech Jankowski, Marcin Hoffmann
Gas phase decompositions of protonated methyl benzoate and its conjugates have been studied by using electrospray ionization-collision induced dissociation-tandem mass spectrometry (ESI-CID-MS/MS). Loss of CO2molecule, thus transfer of methyl group, has been observed. In order to bestter understand this process the theoretical calculations have been performed. For methyl benzoate conjugates, it has been found that position of substituent affects the loss of CO2molecule, not the electron donor/withdrawing properties of the substituent...
February 13, 2018: Journal of Mass Spectrometry: JMS
Adrian Arendowski, Joanna Nizioł, Tomasz Ruman
A new methodology applicable for both - high resolution laser desorption/ionization mass spectrometry and mass spectrometry imaging of amino acids is presented. The MALDI-type target containing monoisotopic cationic 109 Ag nanoparticles (109 AgNPs) was used for rapid mass spectrometry measurements of eleven amino acids of different chemical properties. Amino acids were directly tested in 100000-fold concentration change conditions ranging from 100 μg/mL to 1 ng/mL which equates to 50 ng to 500 fg of amino acid per measurement spot...
February 7, 2018: Journal of Mass Spectrometry: JMS
Yi-Hong Cai, Yi-Sheng Wang
This work discusses the correlation between the mass resolving power of MALDI-TOF mass analyzers and extraction condition with an uneven sample morphology. Previous theoretical calculations show that the optimum extraction condition for flat samples involves an ideal ion source design and extraction delay. A general expression of spectral feature takes into account ion initial velocity and extraction delay is derived in the current study. The new expression extends the comprehensive calculation to uneven sample surfaces and above 90% Maxell-Boltzmann initial velocity distribution of ions to account for imperfect ionization condition...
February 1, 2018: Journal of Mass Spectrometry: JMS
Hanxue Xia, Athula B Attygalle
An ion-mobility mass spectrometry study showed that the preferred O-protonated form of p-aminobenzoic in the gas phase can be converted to the thermodynamically less favored N-protomer by in-source collision-induced ion activation during the ion transfer process from the atmospheric region to the first vacuum region if the humidity is high in the ion source. Upon the addition of water vapor to the nitrogen gas utilized to promote the solid analyte to the gas phase under helium-plasma ionization conditions, the intensity of the ion-mobility arrival-time peak for the N-protomer increased dramatically...
January 29, 2018: Journal of Mass Spectrometry: JMS
Natalia Gutowska, Piotr Seliger, Grzegorz Andrijewski, Grażyna Adamus, Iwona Kwiecień
The novel PNP-lariat ether L with cyclotriphosphazene ring incorporated in the macrocyclic structure was synthesized and checked by the ESI-MS method for the ability to bind different types of ions Ag+ , Ca2+ , Cd2+ , Cu2+ and Pb2+ . Furthermore, the stability constants of the abovementioned ions complexes with the investigated ligand have been determined by direct and competitive potentiometric methods. In order to evaluate the stability of various complexes types and to confirm the way of metal cation binding, the tandem mass spectra (MS/MS) of the investigated ligand and its complexes were taken...
January 19, 2018: Journal of Mass Spectrometry: JMS
Andrea Romano, George B Hanna
Proton Transfer Reaction Time of Flight Mass Spectrometry (PTR-ToF-MS) is a direct injection MS technique, allowing for the sensitive and real-time detection, identification and quantification of volatile organic compounds (VOCs). When aiming to employ PTR-ToF-MS for targeted VOC analysis some methodological questions must be addressed, such as the need to correctly identify product ions, or evaluating the quantitation accuracy. This work proposes a workflow for PTR-ToF-MS method development, addressing the main issues affecting the reliable identification and quantification of target compounds...
January 16, 2018: Journal of Mass Spectrometry: JMS
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