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"Mass calibration"

Leah V Schaffer, Michael R Shortreed, Anthony J Cesnik, Brian L Frey, Stefan K Solntsev, Mark Scalf, Lloyd M Smith
In top-down proteomics, intact proteins are analyzed by tandem mass spectrometry and proteoforms, which are defined forms of a protein with specific sequences of amino acids and localized post-translational modifications, are identified using precursor mass and fragmentation data. Many proteoforms that are detected in the precursor scan (MS1) are not selected for fragmentation by the instrument and therefore remain unidentified in typical top-down proteomic workflows. Our laboratory has developed the open source software program Proteoform Suite to analyze MS1-only intact proteoform data...
January 16, 2018: Analytical Chemistry
Jürgen H Gross
Basic poly(propylene glycols), commercially available under the trade name Jeffamine, are evaluated for their potential use as internal mass calibrants in matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry. Due to their basic amino endgroups Jeffamines are expected to deliver [M+H]+ ions in higher yields than neutral poly(propylene glycols) or poly(ethylene glycols). Aiming at accurate mass measurements and molecular formula determinations by matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry, four Jeffamines (M-600, M-2005, D-400, D-230) were thus compared...
December 2017: European Journal of Mass Spectrometry
Toshinobu Hondo, Kirk R Jensen, Jun Aoki, Michisato Toyoda
A simple, effective accurate mass assignment procedure for a time-of-flight mass spectrometer is desirable. External mass calibration using a mass calibration standard together with an internal mass reference (lock mass) is a common technique for mass assignment, however, using polynomial fitting can result in mass-dependent errors. By using the multi-turn time-of-flight mass spectrometer infiTOF-UHV, we were able to obtain multiple time-of-flight data from an ion monitored under several different numbers of laps that was then used to calculate a mass calibration equation...
December 2017: European Journal of Mass Spectrometry
Abdil Ozdemir, Jung-Lee Lin, Mustafa Gulfen, Szu-Hsueh Lai, Chun-Jen Hsiao, Nelson G Chen, Chung-Hsuan Chen
An ESI ion trap mass spectrometer was designed for high-throughput and rapid mass analysis of large bioparticles. Mass calibration of the instrument was performed using commercially available polystyrene (PS) microparticles with a size comparable to cancer cells. Different sizes of MCF-7 breast cancer cells (8 to 15 μm) were used in this study. The masses of different cancer cells were measured. This system allows for the analysis of all types of particles.
December 19, 2017: Analytical Chemistry
Dalton T Snyder, R Graham Cooks
Reported herein is a simple method of performing single analyzer precursor ion scans in a linear quadrupole ion trap using orthogonal double resonance excitation. A first supplementary AC signal applied to the y electrodes is scanned through ion secular frequencies in order to mass-selectively excite precursor ions while, simultaneously, a second fixed-frequency AC signal is applied orthogonally on the x electrodes in order to eject product ions of selected mass-to-charge ratios towards the detector. The two AC signals are applied orthogonally so as to preclude the possibility of (1) inadvertently ejecting precursor ions into the detector, which results in artifact peaks, and (2) prevent beat frequencies on the x electrodes from ejecting ions off-resonance...
September 2017: Journal of the American Society for Mass Spectrometry
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
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
Chris Bielow, Guido Mastrobuoni, Marica Orioli, Stefan Kempa
Mass-spectrometry-based lipidomics aims to identify as many lipid species as possible from complex biological samples. Due to the large combinatorial search space, unambiguous identification of lipid species is far from trivial. Mass ambiguities are common in direct-injection shotgun experiments, where an orthogonal separation (e.g., liquid chromatography) is missing. Using the rich information within available lipid databases, we generated a comprehensive rule set describing mass ambiguities, while taking into consideration the resolving power (and its decay) of different mass analyzers...
February 21, 2017: Analytical Chemistry
Max W Robinson, Alan P Hill, Simon A Readshaw, John C Hollerton, Richard J Upton, Sean M Lynn, Steve C Besley, Bob J Boughtflower
Universal quantitative detection without the need for analyte reference standards would offer substantial benefits in many areas of analytical science. The quantitative capability of high-performance liquid chromatography (HPLC) with charged aerosol detection (CAD) was investigated for 50 compounds with a wide range of physical and chemical properties. It is widely believed that CAD is a mass detector. Quantification of the 50 compounds using a generic calibrant and mass calibration achieved an average error of 11...
February 7, 2017: Analytical Chemistry
Mathias Butenschoen, Bahman Dehnadi, André H Hoang, Vicent Mateu, Moritz Preisser, Iain W Stewart
The most precise top quark mass measurements use kinematic reconstruction methods, determining the top mass parameter of a Monte Carlo event generator m_{t}^{MC}. Because of hadronization and parton-shower dynamics, relating m_{t}^{MC} to a field theory mass is difficult. We present a calibration procedure to determine this relation using hadron level QCD predictions for observables with kinematic mass sensitivity. Fitting e^{+}e^{-} 2-jettiness calculations at next-to-leading-logarithmic and next-to-next-to-leading-logarithmic order to pythia 8...
December 2, 2016: Physical Review Letters
Dominik Lungerich, Jakob F Hitzenberger, Wolfgang Donaubauer, Thomas Drewello, Norbert Jux
A feasible two-step synthesis and characterization of a full series of hexaarylbenzene (HAB) substituted porphyrins and tetrabenzoporphyrins is presented. Key steps represent the microwave-assisted porphyrin condensation and the statistical Diels-Alder reaction to the desired HAB-porphyrins. Regarding their applications, they proved to be easily accessible and effective high molecular mass calibrants for (MA)LDI mass spectrometry. The free-base and zinc(II) porphyrin systems, as well as the respective tetrabenzoporphyrins, demonstrate in solid state experiments strong red- and near-infrared-light emission and are potentially interesting for the application in "truly organic" light-emitting devices...
November 14, 2016: Chemistry: a European Journal
Dalton T Snyder, Christopher J Pulliam, R Graham Cooks
RATIONALE: Secular frequency scanning is a method of mass selectively scanning ions out of a quadrupole ion trap by linearly ramping the frequency of the resonance ejection signal through ion secular frequencies at constant rf amplitude and frequency. The method is electronically much simpler than resonance ejection but it requires a complex nonlinear calibration procedure to correlate mass-to-charge with time. METHODS: A method of secular frequency scanning in quadrupole ion traps is described in which mass-to-charge is linear with time...
November 30, 2016: Rapid Communications in Mass Spectrometry: RCM
Jiaojie Tan, Jingyu Liu, Mingdong Li, Hind El Hadri, Vincent A Hackley, Michael R Zachariah
The novel hyphenation of electrospray-differential mobility analysis with single particle inductively coupled plasma mass spectrometry (ES-DMA-spICPMS) was demonstrated with the capacity for real-time size, mass, and concentration measurement of nanoparticles (NPs) on a particle-to-particle basis. In this proof-of-concept study, the feasibility of this technique was validated through both concentration and mass calibration using NIST gold NP reference materials. A detection limit of 10(5) NPs mL(-1) was determined under current experimental conditions, which is about 4 orders of magnitude lower in comparison to that of a traditional ES-DMA setup using a condensation particle counter as detector...
September 6, 2016: Analytical Chemistry
Ryan Matsuda, Venkata Kolli, Megan Woods, Eric D Dodds, David S Hage
Sample pretreatment was optimized to obtain high sequence coverage for human serum albumin (HSA, 66.5 kDa) when using nano-electrospray ionization quadrupole time-of-flight mass spectrometry (nESI-Q-TOF-MS). Use of the final method with trypsin, Lys-C, and Glu-C digests gave a combined coverage of 98.8%. The addition of peptide fractionation resulted in 99.7% coverage. These results were comparable to those obtained previously with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS)...
September 15, 2016: Analytical Biochemistry
Jürgen H Gross
A procedure is described that results in a substantial increase in signal intensity and in improved accuracy of positive-ion mass calibration when using commercially available kits of monodisperse dendrimers (SpheriCal(®)) in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). The peak intensities are amplified by an admixture of 2-[(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene] malononitrile (DCTB) matrix to the kits comprising of 9-nitroanthracene matrix, sodium trifluoroacetate, and four dendrimers...
August 2016: Analytical and Bioanalytical Chemistry
Manuel Kasper, Lukas Traxler, Jasmina Salopek, Herwig Grabmayr, Andreas Ebner, Ferry Kienberger
We developed an impedance quartz crystal microbalance (QCM) approach with the ability to simultaneously record mass changes and calibrated energy dissipation with high sensitivity using an impedance analyzer. This impedance QCM measures frequency shifts and resistance changes of sensing quartz crystals very stable, accurately, and calibrated, thus yielding quantitative information on mass changes and dissipation. Resistance changes below 0.3 Ω were measured with corresponding dissipation values of 0.01 µU (micro dissipation units)...
May 25, 2016: Biosensors
Fan Yu, Houqin Fang, Kaijie Xiao, Yan Liu, Bingbing Xue, Zhixin Tian
RATIONALE: The mass measurement accuracy (MMA) of Orbitrap mass spectrometers is 1-5 ppm according to the manufacturer's specification; yet, up to 50 ppm has been used as mass tolerance to interpret Orbitrap data in the literature. A systematic evaluation of MMA is thus necessary to find the optimal mass tolerance to be used. METHODS: Reversed-phase liquid chromatography/tandem mass spectrometry (RPLC/MS/MS) analyses of the intact E. coli proteome were carried out on a Q Exactive Orbitrap mass spectrometer coupled to a Dionex UltiMate 3000 RSLCnano system...
June 30, 2016: Rapid Communications in Mass Spectrometry: RCM
Dalton T Snyder, Christopher J Pulliam, Joshua S Wiley, Jason Duncan, R Graham Cooks
Secular frequency scanning is implemented and characterized using both a benchtop linear ion trap and a miniature rectilinear ion trap mass spectrometer. Separation of tetraalkylammonium ions and those from a mass calibration mixture and from a pesticide mixture is demonstrated with peak widths approaching unit resolution for optimized conditions using the benchtop ion trap. The effects on the spectra of ion trap operating parameters, including waveform amplitude, scan direction, scan rate, and pressure are explored, and peaks at black holes corresponding to nonlinear (higher-order field) resonance points are investigated...
July 2016: Journal of the American Society for Mass Spectrometry
Michael Krappmann, Arjen R de Boer, Daniël R W Kool, Hubertus Irth, Thomas Letzel
RATIONALE: Continuous-flow reaction detection systems (monitoring enzymatic reactions with mass spectrometry (MS)) lack quantitative values so far. Therefore, two independent internal standards (IS) are implemented in a way that the online system stability can be observed, quantitative conversion values for substrate and product can be obtained and they can be used as mass calibration standards for high MS accuracy. METHODS: An application previously developed for the MS detection of peptide phosphorylation by cAMP-dependent protein kinase A (PKA) (De Boer et al...
April 30, 2016: Rapid Communications in Mass Spectrometry: RCM
Till Gruendling, Volker Sauerland, César Barahona, Corinna Herz, Ute Nitsch
RATIONALE: Mass calibration in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is currently obtained using mixtures of individual peptides. This procedure has several drawbacks, including laborious preparation, limited shelf life and unequal calibration mass spacing. Polyalanine, a simple to prepare polydisperse molar mass standard, alleviates these problems. METHODS: Polyalanine is prepared by the typical protocols for biological sample analytics...
March 30, 2016: Rapid Communications in Mass Spectrometry: RCM
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