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Gary M Hieftje - One of the best experts on this subject based on the ideXlab platform.
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zoom tofms additIon of a constant momentum acceleratIon zoom mode to time of flight mass spectrometry
Analytical and Bioanalytical Chemistry, 2014Co-Authors: Elise A Dennis, Steven J Ray, Alexander Gundlachgraham, Christie G Enke, Charles J Barinaga, David W Koppenaal, Gary M HieftjeAbstract:In this study, we demonstrate the performance of a new mass spectrometry concept called zoom time-of-flight mass spectrometry (zoom-TOFMS). In our zoom-TOFMS instrument, we combine two complementary types of TOFMS: conventIonal, constant-energy acceleratIon (CEA) TOFMS and constant-momentum acceleratIon (CMA) TOFMS to provide complete mass-spectral coverage as well as enhanced resolutIon and duty factor for a narrow, targeted mass regIon, respectively. AlternatIon between CEA- and CMA-TOFMS requires only that electrostatic instrument settings (i.e., reflectron and Ion Optics) and Ion acceleratIon conditIons be changed. The prototype zoom-TOFMS instrument has orthogonal-acceleratIon geometry, a total field-free distance of 43 cm, and a direct-current glow-discharge IonizatIon source. Experimental results demonstrate that the CMA-TOFMS “zoom” mode offers resolutIon enhancement of 1.6 times over single-stage acceleratIon CEA-TOFMS. For the atomic mass range studied here, the maximum resolving power at full-width half-maximum observed for CEA-TOFMS was 1,610 and for CMA-TOFMS the maximum was 2,550. No difference in signal-to-noise (S/N) ratio was observed between the operating modes of zoom-TOFMS when both were operated at equivalent repetitIon rates. For a 10-kHz repetitIon rate, S/N values for CEA-TOFMS varied from 45 to 990 and from 67 to 10,000 for CMA-TOFMS. This resolutIon improvement is the result of a linear TOF-to-mass scale and the energy-focusing capability of CMA-TOFMS. Use of CMA also allows Ions outside a given m/z range to be rejected by simple Ion-energy barriers to provide a substantial improvement in duty factor.
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an electrospray inductively coupled plasma dual source time of flight mass spectrometer for rapid metallomic and speciatIon analysis instrument design
Metallomics, 2009Co-Authors: Duane A Rogers, Steven J Ray, Gary M HieftjeAbstract:A time-of-flight mass spectrometer (TOFMS), which employs inductively coupled plasma (ICP) and electrospray IonizatIon (ESI) sources simultaneously, has been designed, constructed, and evaluated for comprehensive elemental speciatIon analysis. The simultaneous operatIon of both sources with a single mass spectrometer is an improvement over existing techniques. The mass analyzer shares a third-stage vacuum system, extractIon regIon, acceleratIon regIon, field-free regIon, and two-stage reflectron between both sources. Most of the other components, such as first and second-stage vacuum systems, pre-extractIon Ion Optics, microchannel plate detectors, and data acquisitIon are independent, to provide the greatest degree of flexibility in source operatIon and signal optimizatIon. A detailed descriptIon is given of the design and optimizatIon of the orthogonal acceleratIon and spontaneous drift geometry, energy discriminatIon, and the reflectron and preliminary performance data are presented.
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advancing the capabilities of a glow discharge sector field mass spectrometer
Journal of Analytical Atomic Spectrometry, 2002Co-Authors: David A Solyom, Gary M HieftjeAbstract:The improved analytical capabilities of a glow-discharge Mattauch–Herzog mass spectrograph are presented. The glow discharge is a desirable analytical source because of its simplicity and direct solids analysis capabilities. The Mattauch–Herzog double-focusing sector geometry produces a linear focal plane, in contrast to the curved focal regIon common to most sector instruments. Placing an array detector along this focal plane allows simultaneous and continuous acquisitIon of data over an entire mass range, whereas an ordinary sector instrument must scan this same range. In this paper, the present capabilities of the mass spectrograph with a glow-discharge source are presented. Due to present-day array-detector limitatIons, mass spectral acquisitIon was performed with an electron multiplier by scanning the magnetic field. Ultimately, a suitable array detector will be incorporated and the data shown here will serve as a reference for future array-detector data. Also considered here is the compatibility between the mass spectrograph and a microsecond pulsed glow discharge source. The pulsed source produces analyte and bulk plasma Ions at different periods within the pulse cycle. This feature, coupled with gated Ion Optics, enhances the determinatIon of species in close mass spectral proximity to bulk plasma Ions. This capability will be particularly useful when an array detector is used because of the inherent susceptibility of such detectors to accidental overexposure from sample-matrix and plasma Ions.
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reducing the energy distributIon in a plasma source sector field mass spectrometer interface
Journal of Analytical Atomic Spectrometry, 1997Co-Authors: Thomas W Burgoyne, Gary M Hieftje, Ronald A HitesAbstract:Ion-beam kinetic-energy distributIons were measured with several sector-field plasma-source mass spectrometer interface configuratIons. The original interface design produced relative energy distributIons of 23% (with an ICP source) and 13% (with a GD source). These relative energy distributIons were independent of the interface potential. Accelerating more evenly and over a shorter distance (with a grid installed) in the second vacuum stage dramatically reduced the relative energy distributIon but also the signal level. The additIon of an ICP torch shield also helped to reduce the relative energy distributIon, presumably by lowering the plasma offset voltage. New Ion Optics were designed with the distance between the apertures leading to the second and third vacuum stages decreased (to roughly 20 mm) and with the majority of the Ion-beam acceleratIon moved from the second to a short distance into the third vacuum regIon. This configuratIon reduced the relative Ion-beam energy distributIon to roughly 5% for both sources but also resulted in some loss of signal.
Diane Beauchemin - One of the best experts on this subject based on the ideXlab platform.
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matrix effects in inductively coupled plasma mass spectrometry a review
Analytica Chimica Acta, 2011Co-Authors: Christian Agatemor, Diane BeaucheminAbstract:Fundamental research on non-spectroscopic interferences, also known as matrix effects, in inductively coupled plasma (ICP) mass spectrometry with sample introductIon using nebulizatIon is critically and exclusively examined in this review, starting with fundamental processes that may be a source of matrix effects during sample introductIon, Ion generatIon in the ICP, Ion extractIon through the interface, and Ion transport through the Ion Optics to the detector. Various methods for attenuating matrix effects are then reviewed and illustrated with some examples. Instead of exhaustively reviewing the literature, representative references are used to comprehensively describe the main issues, several of which are also common to ICP optical emissIon spectrometry.
Michisato Toyoda - One of the best experts on this subject based on the ideXlab platform.
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constructIon of a newly designed small size mass spectrometer for helium isotope analysis toward the continuous monitoring of 3he 4he ratios in natural fluids
Mass spectrometry, 2012Co-Authors: Kenichi Bajo, Michisato Toyoda, Morio Ishihara, Itsuo Katakuse, Hirochika Sumino, Ryuji Okazaki, T Osawa, Kenji NotsuAbstract:The constructIon of a small-size, magnetic sector, single focusing mass spectrometer (He-MS) for the continuous, on-site monitoring of He isotope ratios ((3)He/(4)He) is described. The instrument is capable of measuring (4)He/(20)Ne ratios dissolved in several different types of natural fluids of geochemical interest, such as groundwater and gas from hot springs, volcanoes and gas well fields. The Ion Optics of He-MS was designed using an Ion trajectory simulatIon program "TRIO," which permits the simultaneous measurement of (3)He and (4)He with a double collector system under a mass resolutIon power (M/ΔM) of >700. The presently attained specificatIons of He-MS are; (1) a mass resolving power of ca. 430, sufficient to separate (3)He(+) from interfering Ions, HD(+) and H3 (+), (2) ultra-high vacuum conditIons down to 3×10(-8) Pa, and (3) a sufficiently high sensitivity to permit amounts of (3)He to be detected at levels as small as 10(-13) cm(3) STP (3×10(6) atoms). Long term stability for (3)He/(4)He analysis was examined by measuring the (3)He/(4)He standard gas (HESJ) and atmospheric He, resulting in ∼3% reproducibility and ≤5% experimental error for various amounts of atmospheric He from 0.3 to 2.3×10(-6) cm(3) STP introduced into the instrument. A dynamic range of measurable (3)He/(4)He ratios with He-MS is greater than 10(3) which was determined by measuring various types of natural fluid samples from continental gas (with a low (3)He/(4)He ratio down to 2×10(-8)) to volcanic gas (with a high (3)He/(4)He ratio up to 3×10(-5)). The accuracy and precisIon of (3)He/(4)He and (4)He/(20)Ne ratios were evaluated by comparing the values with those measured using well established noble gas mass spectrometers (modified VG5400/MS-III and -IV) in our laboratory, and were found to be in good agreement within analytical errors. Usefulness of the selective extractIon of He from water/gas using a high permeability of He through a silica glass wall at high temperature (700°C) is demonstrated.
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miniaturized high resolutIon time of flight mass spectrometer multum s ii with an infinite flight path
Analytical Chemistry, 2010Co-Authors: Shuichi Shimma, Hirofumi Nagao, Jun Aoki, Keiji Takahashi, Shinichi Miki, Michisato ToyodaAbstract:A new miniature multiturn time-of-flight (TOF) analyzer “MULTUM-S II” has been designed and constructed. This instrument consists of an electron IonizatIon source, the multiturn TOF Ion Optics, a detector, vacuum system, and electronic circuits. The multiturn TOF analyzer consists of four electrostatic toroidal sectors and two additIonal electric toroidal sectors for the purpose of Ion injectIon/ejectIon. The size and weight of the system is less than 50 cm × 57 cm × 30 cm and 35 kg (including vacuum pumps and electronic circuits). The multiturn TOF analyzer is capable of high mass resolutIon because of its infinite flight path utilizing perfect space and time focused closed flight orbit. To evaluate the resolutIon in MULTUM-S II, separatIon of pyridine (12C5H5N) and the isotopic component of benzene (13C12C5H6) was performed at a mass resolutIon of about 20 000. Another performance characteristic of the MULTUM-S II was demonstrated by the separatIon of the greenhouse gas doublet CO2 and N2O (Δm = 0.0113 ...
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multi turn time of flight mass spectrometers with electrostatic sectors
Journal of Mass Spectrometry, 2003Co-Authors: Michisato Toyoda, Morio Ishihara, Daisuke Okumura, Itsuo KatakuseAbstract:The mass resolutIon of a time-of-flight (TOF) mass spectrometer is directly proportIonal to its total flight pathlength. Multi-turn or multi-passage Ion optical geometries are necessary to obtain fight distances of sufficient length within reasonable size limitatIons. We have investigated Ion Optics for a multi-turn TOF mass spectrometer with electrostatic sectors. The concept of ‘perfect’ focusing conditIons is introduced. Furthermore, a new type of multi-turn TOF mass spectrometer, the MULTUM Linear plus, was developed. It consists of four cylindrical electric sectors and 28 electric quadrupole lenses. It has a vacuum chamber 60 × 70 × 20 cm in size. Mass resolutIon is demonstrated to increase according to the number of Ion cycles. A mass resolutIon of 350 000 (m/z = 28, FWHM) was achieved after 501.5 cycles. The MULTUM Linear plus analyzer is not simple, however; 28 electric quadrupole lenses are used. In order to reduce the number of Ion optical parts, an improved multi-turn TOF mass spectrometer, the MULTUM II, consisting of only four toroidal electric sectors, was also developed. The possibility of tandem mass spectrometric applicatIons using multi-turn TOF mass spectrometers is also discussed. Copyright © 2003 John Wiley & Sons, Ltd.
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perfect space and time focusing Ion Optics for multiturn time of flight mass spectrometers
International Journal of Mass Spectrometry, 2000Co-Authors: Morio Ishihara, Michisato Toyoda, Takekiyo MatsuoAbstract:Abstract Ion Optics of multiturn time-of-flight mass spectrometer that satisfy both perfect space and time focusing were investigated. The basic concepts of perfect focusing are explained. It was found that the perfect focusing conditIons can be reduced by introducing symmetrical geometries. The conditIons are expressed in the transfer matrix form.
Scott A Shaffer - One of the best experts on this subject based on the ideXlab platform.
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comparison of data acquisitIon strategies on quadrupole Ion trap instrumentatIon for shotgun proteomics
Journal of the American Society for Mass Spectrometry, 2014Co-Authors: Jesse D. Canterbury, Michael J Maccoss, Gennifer E Merrihew, David R Goodlett, Scott A ShafferAbstract:The most common data collectIon in shotgun proteomics is via data-dependent acquisitIon (DDA), a process driven by an automated instrument control routine that directs MS/MS acquisitIon from the highest abundant signals to the lowest. An alternative to DDA is data-independent acquisitIon (DIA), a process in which a specified range in m/z is fragmented without regard to prioritizatIon of a precursor Ion or its relative abundance in the mass spectrum, thus potentially offering a more comprehensive analysis of peptides than DDA. In this work, we evaluate both DDA and DIA on three different linear Ion trap instruments: an LTQ, an LTQ modified with an electrodynamic Ion funnel, and an LTQ Velos. These instruments represent both older (LTQ) and newer (LTQ Velos) Ion trap designs (i.e., linear versus dual Ion traps, respectively), and allow direct comparison of peptide identificatIons using both DDA and DIA analysis. Further, as the LTQ Velos has an enhanced “S-lens” Ion guide to improve Ion flux, we found it logical to determine if the former LTQ model could be leveraged by improving sensitivity by modifying with an electrodynamic Ion guide of significantly different design to the S-lens. We find that the Ion funnel enabled LTQ identifies more proteins in the insoluble fractIon of a yeast lysate than the other two instruments in DIA mode, whereas the faster scanning LTQ Velos performs better in DDA mode. We explore reasons for these results, including differences in scan speed, source Ion Optics, and linear Ion trap design.
Christian Agatemor - One of the best experts on this subject based on the ideXlab platform.
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matrix effects in inductively coupled plasma mass spectrometry a review
Analytica Chimica Acta, 2011Co-Authors: Christian Agatemor, Diane BeaucheminAbstract:Fundamental research on non-spectroscopic interferences, also known as matrix effects, in inductively coupled plasma (ICP) mass spectrometry with sample introductIon using nebulizatIon is critically and exclusively examined in this review, starting with fundamental processes that may be a source of matrix effects during sample introductIon, Ion generatIon in the ICP, Ion extractIon through the interface, and Ion transport through the Ion Optics to the detector. Various methods for attenuating matrix effects are then reviewed and illustrated with some examples. Instead of exhaustively reviewing the literature, representative references are used to comprehensively describe the main issues, several of which are also common to ICP optical emissIon spectrometry.
