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Journal of the American Society for Mass Spectrometry

Kelsey S Boes, Michael S Roberts, Nelson R Vinueza
Complex mixture analysis is a costly and time-consuming task facing researchers with foci as varied as food science and fuel analysis. When faced with the task of quantifying oxygen-rich bio-oil molecules in a complex diesel mixture, we asked whether complex mixtures could be qualitatively and quantitatively analyzed on a single mass spectrometer with mid-range resolving power without the use of lengthy separations. To answer this question, we developed and evaluated a quantitation method that eliminated chromatography steps and expanded the use of quadrupole-time-of-flight mass spectrometry from primarily qualitative to quantitative as well...
December 12, 2017: Journal of the American Society for Mass Spectrometry
Aneesh Prabhakaran, Ahmed M Hamid, Sandilya V B Garimella, Blandina R Valenzuela, Robert G Ewing, Yehia M Ibrahim, Richard D Smith
Here we explore the combination of constant and oscillatory fields applied in a single device to affect the continuous separation and filtering of ions based on their mobilities. The device explored allows confining and manipulating ions utilizing a combination of radio frequency (rf), direct current (DC) fields, and traveling waves (TW) in a structures for lossless ion manipulations (SLIM) module. We have investigated theoretically and experimentally a concept for continuous filtering of ions based on their mobilities where ions are mobility separated and selected by passage through two regions, both of which incorporated combined TW and constant fields providing opposing forces on the ions...
December 12, 2017: Journal of the American Society for Mass Spectrometry
Alexandre K Tashima, Lloyd D Fricker
Quantitative peptidomics and proteomics often use chemical tags to covalently modify peptides with reagents that differ in the number of stable isotopes, allowing for quantitation of the relative peptide levels in the original sample based on the peak height of each isotopic form. Different chemical reagents have been used as tags for quantitative peptidomics and proteomics, and all have strengths and weaknesses. One of the simplest approaches uses formaldehyde and sodium cyanoborohydride to methylate amines, converting primary and secondary amines into tertiary amines...
December 12, 2017: Journal of the American Society for Mass Spectrometry
Craig A Stinson, Wenpeng Zhang, Yu Xia
Ozonolysis of alkene functional groups is a type of highly specific and effective chemical reaction, which has found increasing applications in structural analysis of unsaturated lipids via coupling with mass spectrometry (MS). In this work, we utilized a low-pressure mercury lamp (6 W) to initiate ozonolysis inside electrospray ionization (ESI) sources. By placing the lamp near a nanoESI emitter that partially transmits 185 nm ultraviolet (UV) emission from the lamp, dissolved dioxygen in the spray solution was converted into ozone, which subsequently cleaved the double bonds within fatty acyls of lipids...
December 12, 2017: Journal of the American Society for Mass Spectrometry
Hsu Chen Hsu, Chia Yen Liew, Shih-Pei Huang, Shang-Ting Tsai, Chi-Kung Ni
Oligosaccharides have diverse functions in biological systems. However, the structural determination of oligosaccharides remains difficult and has created a bottleneck in carbohydrate research. In this study, a new approach for the de novo structural determination of underivatized oligosaccharides is demonstrated. A low-energy collision-induced dissociation (CID) of sodium ion adducts was used to facilitate the cleavage of desired chemical bonds during the dissociation. The selection of fragments for the subsequent CID was guided using a procedure that we built from the understanding of the saccharide dissociation mechanism...
December 12, 2017: Journal of the American Society for Mass Spectrometry
Brian J Malys, Michelle L Piotrowski, Kevin G Owens
Frustrated by worse than expected error for both peak area and time-of-flight (TOF) in matrix assisted laser desorption ionization (MALDI) experiments using samples prepared by electrospray deposition, it was finally determined that there was a correlation between sample location on the target plate and the measured TOF/peak area. Variations in both TOF and peak area were found to be due to small differences in the initial position of ions formed in the source region of the TOF mass spectrometer. These differences arise largely from misalignment of the instrument sample stage, with a smaller contribution arising from the non-ideal shape of the target plates used...
December 7, 2017: Journal of the American Society for Mass Spectrometry
Xin Liu, Colin Flinders, Shannon M Mumenthaler, Amanda B Hummon
Patient-derived colorectal tumor organoids (CTOs) closely recapitulate the complex morphological, phenotypic, and genetic features observed in in vivo tumors. Therefore, evaluation of drug distribution and metabolism in this model system can provide valuable information to predict the clinical outcome of a therapeutic response in individual patients. In this report, we applied matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to examine the spatial distribution of the drug irinotecan and its metabolites in CTOs from two patients...
December 5, 2017: Journal of the American Society for Mass Spectrometry
Ludmyla S Tavares, Thays C Carvalho, Wanderson Romão, Boniek G Vaz, Andréa R Chaves
This study proposes a new direct and fast method of analysis employing paper spray mass spectrometry (PS-MS). The paper used in the proposed method was modified with molecularly imprinted polymers (MIP) to create a specific site for cocaine analysis in oral fluid. MIP membrane was successfully synthetized and employed. The developed method showed to be linear in a concentration range from LOQ to 100 ng mL-1. The experimental value of LOQ obtained was 1 ng mL-1. The inter-day and intra-day precision and accuracy of the PS-MS method presented values lower than 15%...
December 1, 2017: Journal of the American Society for Mass Spectrometry
Tyler J Yarger, Elizabeth M Yuill, Lane A Baker
We introduce probe-substrate distance (Dps)-control to desorption electrospray ionization (DESI) and report a systematic investigation of key experimental parameters. Examination of voltage, flow rate, and nebulizing gas pressure suggests as Dps decreases, the distance-dependent spray current increases, until a critical point. At the critical point the relationship inverts, and the spray current decreases as the probe moves closer to the surface due to constriction of solution flow by the nebulizing gas. Dps control was used to explore the use of spray current as a signal for feedback positioning, while mass spectrometry imaging was performed simultaneously...
November 27, 2017: Journal of the American Society for Mass Spectrometry
Nathan M Sindt, Faith Robison, Mark A Brick, Howard F Schwartz, Adam L Heuberger, Jessica E Prenni
Matrix-assisted desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) is a fast and effective tool for microbial species identification. However, current approaches are limited to species-level identification even when genetic differences are known. Here, we present a novel workflow that applies the statistical method of partial least squares discriminant analysis (PLS-DA) to MALDI-TOF-MS protein fingerprint data of Xanthomonas axonopodis, an important bacterial plant pathogen of fruit and vegetable crops...
November 27, 2017: Journal of the American Society for Mass Spectrometry
Claude Poleunis, Vanina Cristaudo, Arnaud Delcorte
In this work, time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to study the intensity variations of the backscattered Arn+ clusters as a function of temperature for several amorphous polymer surfaces (polyolefins, polystyrene, and polymethyl methacrylate). For all these investigated polymers, our results show a transition of the ratio Ar2+/(Ar2+ + Ar3+) when the temperature is scanned from -120 °C to +125 °C (the exact limits depend on the studied polymer). This transition generally spans over a few tens of degrees and the temperature of the inflection point of each curve is always lower than the bulk glass transition temperature (Tg) reported for the considered polymer...
November 27, 2017: Journal of the American Society for Mass Spectrometry
Sam B Choi, Camille Lombard-Banek, Pablo Muñoz-LLancao, M Chiara Manzini, Peter Nemes
The ability to detect peptides and proteins in single cells is vital for understanding cell heterogeneity in the nervous system. Capillary electrophoresis (CE) nanoelectrospray ionization (nanoESI) provides high-resolution mass spectrometry (HRMS) with trace-level sensitivity, but compressed separation during CE challenges protein identification by tandem HRMS with limited MS/MS duty cycle. Here, we supplemented ultrasensitive CE-nanoESI-HRMS with reversed-phase (RP) fractionation to enhance identifications from protein digest amounts that approximate to a few mammalian neurons...
November 16, 2017: Journal of the American Society for Mass Spectrometry
Yuxue Liang, Pedatsur Neta, Xiaoyu Yang, Stephen E Stein
High-accuracy MS/MS spectra of deprotonated ions of 390 dipeptides and 137 peptides with three to six residues are studied. Many amino acid residues undergo neutral losses from their side chains. The most abundant is the loss of acetaldehyde from threonine. The abundance of losses from the side chains of other amino acids is estimated relative to that of threonine. While some amino acids lose the whole side chain, others lose only part of it, and some exhibit two or more different losses. Side-chain neutral losses are less abundant in the spectra of protonated peptides, being significant mainly for methionine and arginine...
November 15, 2017: Journal of the American Society for Mass Spectrometry
Alexander D Jacobs, K V Jovan Jose, Rachel Horness, Krishnan Raghavachari, Megan C Thielges, David E Clemmer
Ion mobility spectrometry-mass spectrometry and Fourier transform infrared spectroscopy (FTIR) techniques were combined with quantum chemical calculations to examine the origin of icosahedral clusters of the amino acid proline. When enantiopure proline solutions are electrosprayed (using nanospray) from 100 mM ammonium acetate, only three peaks are observed in the mass spectrum across a concentration range of five orders of magnitude: a monomer [Pro+H](+) species, favored from 0.001 to 0.01 mM proline concentrations; a dimer [2Pro+H](+) species, the most abundant species for proline concentrations above 0...
November 10, 2017: Journal of the American Society for Mass Spectrometry
Konstantin O Nagornov, Anton N Kozhinov, Yury O Tsybin
Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) at the cyclotron frequency instead of the reduced cyclotron frequency has been experimentally demonstrated using narrow aperture detection electrode (NADEL) ICR cells. Here, based on the results of SIMION simulations, we provide the initial mechanistic insights into the cyclotron frequency regime generation in FT-ICR MS. The reason for cyclotron frequency regime is found to be a new type of a collective motion of ions with a certain dispersion in the initial characteristics, such as pre-excitation ion velocities, in a highly non-quadratic trapping potential as realized in NADEL ICR cells...
November 8, 2017: Journal of the American Society for Mass Spectrometry
Kevin Colizza, Alexander Yevdokimov, Lindsay McLennan, James L Smith, Jimmie C Oxley
Over the last several decades, mass spectrometry has become one of the principle methods for compound identification and quantification. While for analytical purposes, fragments which are not fully characterized in terms of origin and intensity as a function of experimental conditions have been used, understanding the nature of those species is very important. Herein we discuss such issues relative to triacetone triperoxide (TATP) and its frequently observed fragment at m/z 89. This "fragment" has been identified as the gas-phase reaction product of TATP with one or two methanol molecules/ions...
November 7, 2017: Journal of the American Society for Mass Spectrometry
Katrina Brendle, Max Kordel, Erik Schneider, Danny Wagner, Stefan Bräse, Patrick Weis, Manfred M Kappes
We have determined breakdown curves for a range of multiply charged benzylpyridinium-substituted porphyrin cations by collision induced dissociation measurements (CID) as mediated by resonant pulsed radio-frequency (rf) excitation in a helium-filled linear ion trap. Measurements were compared with the predictions of DFT calculations. We find a linear correlation between experimental fragmentation thresholds (in instrumental units of "normalized collision energy") and theoretical dissociation energies, suggesting that these species can be used as calibrants to gauge the fragmentation energetics of closely related systems...
October 30, 2017: Journal of the American Society for Mass Spectrometry
Dario Dabić, Lidija Brkljačić, Tana Tandarić, Mladen Žinić, Robert Vianello, Leo Frkanec, Renata Kobetić
Gels formed by self-assembly of small organic molecules are of wide interest as dynamic soft materials with numerous possible applications, especially in terms of nanotechnology for functional and responsive biomaterials, biosensors, and nanowires. Four bis-oxalamides were chosen to show if electrospray ionization mass spectrometry (ESI-MS) could be used as a prediction of a good gelator and also to shed light on the gelation processes. By inspecting the gelation of several solvent, we showed that bis(amino acid)oxalamide 1 proved to be the most efficient, also being able of forming the largest observable assemblies in the gas phase...
October 30, 2017: Journal of the American Society for Mass Spectrometry
Sarah Trimpin, I-Chung Lu, Stephan Rauschenbach, Khoa Hoang, Beixi Wang, Nicholas D Chubatyi, Wen-Jing Zhang, Ellen D Inutan, Milan Pophristic, Alexander Sidorenko, Charles N McEwen
Ionization processes have been discovered by which small and large as well as volatile and nonvolatile compounds are converted to gas-phase ions when associated with a matrix and exposed to sub-atmospheric pressure. Here, we discuss experiments further defining these simple and unexpected processes. Charge separation is found to be a common process for small molecule chemicals, solids and liquids, passed through an inlet tube from a higher to a lower pressure region, with and without heat applied. This charge separation process produces positively- and negatively-charged particles with widely different efficiencies depending on the compound and its physical state...
October 27, 2017: Journal of the American Society for Mass Spectrometry
Maja K Cieplak-Rotowska, Krzysztof Tarnowski, Marcin Rubin, Marc R Fabian, Nahum Sonenberg, Michal Dadlez, Anna Niedzwiecka
The human GW182 protein plays an essential role in micro(mi)RNA-dependent gene silencing. miRNA silencing is mediated, in part, by a GW182 C-terminal region called the silencing domain, which interacts with the poly(A) binding protein and the CCR4-NOT deadenylase complex to repress protein synthesis. Structural studies of this GW182 fragment are challenging due to its predicted intrinsically disordered character, except for its RRM domain. However, detailed insights into the properties of proteins containing disordered regions can be provided by hydrogen-deuterium exchange mass spectrometry (HDX/MS)...
October 27, 2017: Journal of the American Society for Mass Spectrometry
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