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Gary L. Glish - One of the best experts on this subject based on the ideXlab platform.
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Encyclopedia of Drug Metabolism and InteractIons - Triple Quadrupole and Quadrupole Ion Trap Mass Spectrometers
Encyclopedia of Drug Metabolism and Interactions, 2012Co-Authors: Mark Ridgeway, Gary L. GlishAbstract:Mass spectrometers based on Ion separatIon using electrodynamic quadrupolar fields have been dominant in the evolutIon of the field of mass spectrometry. This chapter discusses triple Quadrupole mass spectrometers and Quadrupole Ion Trap mass spectrometers, two of the most important and commercially successful instruments in the history of mass spectrometry. An overview of the principles of operatIon is discussed in terms of the Mathieu stability diagram, a well-known graphical representatIon to determine whether Ions will have stable or unstable trajectories in a radio frequency (RF) electric field. A brief introductIon of tandem mass spectrometry (MS/MS) is also presented. After the general introductIon, each type of instrument is discussed individually. A brief historical background is provided for each type of instrument. Finally, there is an overview of the wide array of methods to perform MS/MS experiments. Keywords: triple Quadrupole; Quadrupole Ion Trap; MS/MS; Ion activatIon; linear Ion Trap
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Tandem mass spectrometric methods for the analysis of iTRAQ labeled peptides in a Quadrupole Ion Trap
International Journal of Mass Spectrometry, 2011Co-Authors: Atim A. Enyenihi, John R. Griffiths, Gary L. GlishAbstract:Abstract Alternative Ion activatIon methods in a Quadrupole Ion Trap mass spectrometer (QITMS) have been studied to determine their utility for iTRAQ. The collisIonal activatIon methods, thermally assisted CID (TA-CID) and high amplitude short time excitatIon (HASTE) CID, allow the low-mass cut-off (LMCO) to be reduced to ∼10% of the parent Ion mass-to-charge ratio allowing the iTRAQ reporter Ions to be Trapped and detected. An alternative to CID for Ion activatIon/dissociatIon in a QITMS is infrared multiphoton photodissociatIon (IRMPD), which can be performed at LMCOs of
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Improving IRMPD in a Quadrupole Ion Trap
Journal of the American Society for Mass Spectrometry, 2009Co-Authors: G. Asher Newsome, Gary L. GlishAbstract:A focused laser is used to make infrared multiphoton photodissociatIon (IRMPD) more efficient in a Quadrupole Ion Trap mass spectrometer. Efficient (up to 100%) dissociatIon at the standard operating pressure of 1 × 10−3 Torr can be achieved without any supplemental Ion activatIon and with shorter irradiatIon times. The axial amplitudes of Trapped Ion clouds are measured using laser tomography. Laser flux on the Ion cloud is increased six times by focusing the laser so that the beam waist approximates the Ion cloud size. Unmodified peptide Ions from 200 Da to 3 kDa are completely dissociated in 2.5–10 ms at a bath gas pressure of 3.3 × 10−4 Torr and in 3–25 ms at 1.0 × 10−3 Torr. Sequential dissociatIon of product Ions is increased by focusing the laser and by operating at an increased bath gas pressure to minimize the size of the Ion cloud.
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CollisIonal cooling in a Quadrupole Ion Trap at sub-ambient temperatures
International Journal of Mass Spectrometry, 2007Co-Authors: Philip M. Remes, Gary L. GlishAbstract:Abstract Quadrupole Ion Traps have been used successfully as Ion storage devices for infrared multiphoton dissociatIon (IRMPD) experiments. Recently there has been interest in doing low temperature actIon spectroscopy experiments using Ion Traps as detectors for IRMPD spectroscopy. Cooling the Trapping electrodes has the effect of cooling the Trapped Ions to the same internal temperature, because Quadrupole Ion Traps operate at He bath gas pressures high enough to produce equilibrium Ion internal energy distributIons. It has previously been shown that collisIons of the Ions with the bath gas cool the Ions’ internal vibratIonal modes at a rate that competes with IRMPD excitatIon at ambient temperatures. To investigate the implicatIons of doing IRMPD in a Quadrupole Ion Trap at lower Trapping temperatures, the present study measures the collisIonal cooling rate constants at sub-ambient temperatures down to 25 K. The change in collisIonal cooling rate constant with Trap temperature is correlated to the increased energy needed to dissociate the Ions at these lower Trap temperatures. It is found that both the energy needed to effect dissociatIon and the collisIonal cooling rate increase exponentially as Trap temperature drops.
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DeterminatIon of Cooling Rates in a Quadrupole Ion Trap
Journal of the American Society for Mass Spectrometry, 2006Co-Authors: David M. Black, Anne H. Payne, Gary L. GlishAbstract:CollisIonal cooling rates of infrared excited Ions are measured in a Quadrupole Ion Trap (QIT) mass spectrometer at different combinatIons of temperature and pressure. Measurements are carried out by monitoring fragmentatIon efficiency of leucine enkephalin as a functIon of irradiatIon time by an infrared laser after a short excitatIon and incrementally increasing cooling periods. Cooling rates are observed to be directly related to bath gas pressure and inversely related to bath gas temperature. The cooling rate at typical Ion Trap operating pressure (1 mTorr) and temperature (room T) is faster than can be measured. At elevated temperature and the lowest pressure used for the studies, the rate of collisIonal cooling becomes negligible compared to the rate of radiative cooling.
George R. Agnes - One of the best experts on this subject based on the ideXlab platform.
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Plasticizer contaminatIon from vacuum system o-rings in a Quadrupole Ion Trap mass spectrometer
Journal of the American Society for Mass Spectrometry, 2002Co-Authors: Kent M. Verge, George R. AgnesAbstract:The outgassing of plasticizers from Buna-N and Viton o-rings under vacuum lead to undesired Ion-molecule chemistry in an Electrospray Quadrupole Ion Trap Mass Spectrometer. In experiments with the helium bath gas pressure >1.2 mTorr, or whenever analyte Ions were stored for >100 ms, extensive loss of analyte Ions by proton transfer or adductIon with o-ring plasticizers bis(2-ethylhexyl) phthalate and bis(2-ethylhexyl) adipate occurred. A temporary solutIon to this contaminatIon problem was found to be overnight refluxing in hexane of all the o-rings in the vacuum system. This procedure alleviated this plasticizer contaminatIon for ∼100 hours of operatIon. These results, and those that lead to identificatIon of the contaminatIon as plasticizers outgassing from o-rings are described.
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Plasticizer contaminatIon from vacuum system o-rings in a Quadrupole Ion Trap mass spectrometer
Journal of the American Society for Mass Spectrometry, 2002Co-Authors: Kent M. Verge, George R. AgnesAbstract:The outgassing of plasticizers from Buna-N and Viton o-rings under vacuum lead to undesired Ion-molecule chemistry in an Electrospray Quadrupole Ion Trap Mass Spectrometer. In experiments with the helium bath gas pressure >1.2 mTorr, or whenever analyte Ions were stored for >100 ms, extensive loss of analyte Ions by proton transfer or adductIon with o-ring plasticizers bis(2-ethylhexyl) phthalate and bis(2-ethylhexyl) adipate occurred. A temporary solutIon to this contaminatIon problem was found to be overnight refluxing in hexane of all the o-rings in the vacuum system. This procedure alleviated this plasticizer contaminatIon for ∼100 hours of operatIon. These results, and those that lead to identificatIon of the contaminatIon as plasticizers outgassing from o-rings are described.
Richard A. Yost - One of the best experts on this subject based on the ideXlab platform.
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detectIon of pharmaceutical compounds in tissue by matrix assisted laser desorptIon IonizatIon and laser desorptIon chemical IonizatIon tandem mass spectrometry with a Quadrupole Ion Trap
Journal of the American Society for Mass Spectrometry, 1999Co-Authors: Frederick J Troendle, Christopher D Reddick, Richard A. YostAbstract:A novel Quadrupole Ion Trap mass spectrometer laser microprobe instrument with an external IonizatIon source was constructed and used to investigate the matrix-assisted laser desorptIon/IonizatIon (MALDI) detectIon of pharmaceutical compounds in intact tissue. In additIon to MALDI, laser desorptIon coupled with chemical IonizatIon (LD/CI) was investigated. MALDI, using 2,5-dihydroxybenezoic acid (DHB) as a matrix, was employed to detect the anticancer drug paclitaxel from a thin sectIon of rat liver tissue which had been incubated in a solutIon of paclitaxel. The results of that experiment showed that the ability to perform tandem mass spectrometry (MS/MS) with the Quadrupole Ion Trap was crucial in the identificatIon of drug compounds at trace levels in the complex tissue matrix. MALDI MS/MS was then used to detect the presence of paclitaxel in a human ovarian tumor at a concentratIon of approximately 50 mg/kg. Finally, the drug spiperone was detected in incubated rat liver tissue at an approximate level of 25 mg/kg using LD/CI (no MALDI matrix). Again, the MS/MS capability of the Quadrupole Ion Trap was crucial in the identificatIon of the drug at trace levels in the complex tissue matrix.
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DetectIon of pharmaceutical compounds in tissue by matrix-assisted laser desorptIon/IonizatIon and laser desorptIon/chemical IonizatIon tandem mass spectrometry with a Quadrupole Ion Trap
Journal of the American Society for Mass Spectrometry, 1999Co-Authors: Frederick J Troendle, Christopher D Reddick, Richard A. YostAbstract:A novel Quadrupole Ion Trap mass spectrometer laser microprobe instrument with an external IonizatIon source was constructed and used to investigate the matrix-assisted laser desorptIon/IonizatIon (MALDI) detectIon of pharmaceutical compounds in intact tissue. In additIon to MALDI, laser desorptIon coupled with chemical IonizatIon (LD/CI) was investigated. MALDI, using 2,5-dihydroxybenezoic acid (DHB) as a matrix, was employed to detect the anticancer drug paclitaxel from a thin sectIon of rat liver tissue which had been incubated in a solutIon of paclitaxel. The results of that experiment showed that the ability to perform tandem mass spectrometry (MS/MS) with the Quadrupole Ion Trap was crucial in the identificatIon of drug compounds at trace levels in the complex tissue matrix. MALDI MS/MS was then used to detect the presence of paclitaxel in a human ovarian tumor at a concentratIon of approximately 50 mg/kg. Finally, the drug spiperone was detected in incubated rat liver tissue at an approximate level of 25 mg/kg using LD/CI (no MALDI matrix). Again, the MS/MS capability of the Quadrupole Ion Trap was crucial in the identificatIon of the drug at trace levels in the complex tissue matrix.
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Fundamental studies of Ion injectIon and Trapping of electrosprayed Ions on a Quadrupole Ion Trap
International Journal of Mass Spectrometry, 1999Co-Authors: Scott T. Quarmby, Richard A. YostAbstract:Abstract The Quadrupole Ion Trap is a highly versatile and sensitive analytical mass spectrometer. Because of the advantages offered by the Ion Trap, there has been intense interest in coupling it to IonizatIon techniques such as electrospray which form Ions externally to the Ion Trap. In this work, simulatIon and experiment were employed to study the injectIon of electrosprayed Ions into the Quadrupole Ion Trap in a Finnigan MAT LCQ LC/MS n mass spectrometer. SIMIon v6.0 was chosen for the simulatIon studies because it allowed the actual Ion Trap electrode geometry including endcap holes to be simulated. The endcap holes weaken the rf Trapping field in the regIon near the holes; this distortIon of the field is important when Ions have large axial excursIons as they do in Ion injectIon. In additIon, the field penetrates out the endcap holes and affects Ions as they approach the Ion Trap. The results of simulating Ions started outside the Ion Trap agreed well with experimentally obtained Ion injectIon data of the effect of q z during injectIon. From these simulatIons, a model for the process by which injected Ions are Trapped was developed. Injected Ions can be Trapped even with the modest helium buffer gas pressures commonly used (≈1 mTorr) because Ions naturally oscillate for long times (and therefore distances) at certain q z values and initial rf phases. This allows enough collisIons to occur to damp the Ions’ excess kinetic energy.
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Infrared multiple photon dissociatIon in the Quadrupole Ion Trap via a multipass optical arrangement
Journal of the American Society for Mass Spectrometry, 1994Co-Authors: James L. Stephenson, Matthew M. Booth, Joseph A. Shalosky, John R. Eyler, Richard A. YostAbstract:The design of a novel multipass optical arrangement for use with infrared multiple photon dissociatIon (IRMPD) in the Quadrupole Ion Trap is presented. This design circumvents previous problems of limited IR laser power, small IR absorptIon cross sectIons for many molecules, and the limited Ion statistics of Trapping and detectIon of Ions for IRMPD in the Quadrupole Ion Trap. In contrast to previous designs that utilized the Quadrupole Ion store, the Quadrupole Ion Trap was operated in the mass selective instability mode with concurrent resonance ejectIon. The instrumental design consisted of a modified ring electrode with three spherical concave mirrors mounted on the inner surface of the ring. This modified design allowed for eight laser passes across the radial plane of the ring electrode. IRMPD of protonated bis(2-methoxyethyl)ether (diglyme) was used to characterize the performance of the multipass ring electrode. Two consecutive reactIons for the IRMPD of protonated diglyme were observed with a lower energy channel predominant at less than 0.6 J (irradiatIon times from 1 to 30 ms) and a second channel predominant at energies greater than 0.6 J (irradiatIon times > 30 ms). Other studies presented include a discussIon of the dissociatIon kinetics of protonated diglyme, the use of a pulsed valve for increased Trapping efficiency of parent Ion populatIons, and the effects of laser wavelength and of Ion residence time in the radial plane of the ring electrode on photodissociatIon efficiency.
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Nonlinear resonance effects during Ion storage in a Quadrupole Ion Trap.
Journal of the American Society for Mass Spectrometry, 1993Co-Authors: Donald M. Eades, Jodie V. Johnson, Richard A. YostAbstract:ContributIons of higher-order fields to the quadrupolar storage field produce nonlinear resonances in the Quadrupole Ion Trap. Storing Ions with secular frequencies corresponding to these nonlinear resonances allows absorptIon of power from the higher-order fields. This results in increased axial and radial amplitudes which can cause Ion ejectIon and collisIon-induced dissociatIon (CID). Experiments employing long storage times and/or high Ion populatIons, such as chemical IonizatIon, Ion-molecule reactIon studies, and resonance excitatIon CID, can be particularly susceptible to nonlinear resonance effects. The effects of higher-order fields on stored Ions are presented and the influence of instrumental parameters such as radiofrequency and direct current voltage (qZ and az values), Ion populatIon, and storage time are discussed.
Raymond E. March - One of the best experts on this subject based on the ideXlab platform.
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Quadrupole Ion Trap mass spectrometry
2005Co-Authors: Raymond E. MarchAbstract:The Quadrupole Ion Trap (QIT) is constructed of three electrodes that, when held at appropriate potentials, cause the formatIon of a Trapping pseudo-potential well so that charged particles, or gaseous Ions, may be confined or stored for long periods of time. The two end-cap electrodes resemble saucers while the ring electrode resembles a napkin ring; all of the electrodes are of hyperbolic geometry. The Ion Trap itself functIons as a mass spectrometer when the Ion-confining conditIons are modified such that Ions are ejected mass-selectively from the Trapping potential well. As Ions of successive mass/charge ratios are ejected in turn from the Ion Trap, they impinge upon an external detector whereby Ion signals are created in proportIon to the Ion number of each species; in this manner, a mass spectrum is generated. The QITMS (Quadrupole Ion Trap mass spectrometer) is an extraordinary instrument in that it is physically small (the entire electrode assembly can be held in the palm of one's hand) compared with magnetic and electric sector instruments, it is relatively inexpensive, it is one of the most, if not the most, sensitive mass spectrometers and, since several mass-selective operatIons can be carried in successIon, the Ion Trap can functIon as a tandem mass spectrometer. Tandem mass spectrometric operatIon is described as (MS)n. With the QITMS, (MS)n is carried out in time in the same volume of space whereas (MS)n in sector instruments is carried out in space. With sector instruments, the maximum value of n is n = 4 yet with the Ion Trap, (MS)n where n = 4–6 can be carried out routinely and n = 13 has been achieved. The QITMS shares several similarities with the Ion cyclotron resonance mass spectrometer yet the cost of the former is about one-tenth that of the latter. One striking difference between the QITMS and all other mass spectrometers is that the QITMS operates at a pressure of 10−3 Torr compared with 10−6 to 10−9 Torr for other mass spectrometers. The theory of Ion confinement and Ion trajectory manipulatIon in the QITMS has been explained relatively simply so far. Since the theory differs widely from those of sector instruments and Ion cyclotron resonance mass spectrometry (ICR/MS), it will not be familiar to those who have not had the opportunity to examine Ion motIon in Quadrupole fields. Optimum operatIon of the QITMS is effected by collisIonal focusing of the Ion cloud to the center of the Ion Trap under the influence of helium buffer gas. Since the movement of Ions confined in the Ion Trap is periodic, the trajectories of collisIonally focused Ions can be expanded by resonance excitatIon effected by the impositIon of supplementary radio frequency (rf) potentials of low amplitude to the end-cap electrodes of the Ion Trap. This excitatIon operatIon permits isolatIon of selected Ion species, by ejectIon of unwanted Ion species, followed by selective Ion/molecule reactIon or by collisIon-induced dissociatIon (CID) with subsequent mass analysis of the product/fragment Ions formed. Sample calculatIons are given of all of the relevant Trapping parameters. ApplicatIons of the QITMS as a single stage mass spectrometer and as a tandem mass spectrometer are discussed. The operatIon of the QITMS for the identificatIon of dioxins and furans co-eluting from a gas chromatograph is described. In additIon, the applicatIon of chemical IonizatIon (CI) for the identificatIon of co-eluting polychlorinated biphenyl (PCB) congeners is discussed. The QITMS is an extraordinary instrument that is capable of great sensitivity, high mass range and high mass resolutIon. Since the QITMS is compatible with methods for generating Ions externally, such as electrospray IonizatIon (ESI), its continued growth in many areas of mass spectrometry (MS) is assured. The structural details of the glycoprotein and the optical spectroscopy of stored Ions are applicatIons of the QITMS combined with ESI, while the Ion Trap in combinatIon with a metal-cluster aggregatIon source has been used for an electron diffractIon study.
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Quadrupole Ion Trap mass spectrometry: a view at the turn of the century
International Journal of Mass Spectrometry, 2000Co-Authors: Raymond E. MarchAbstract:A personal account of the Quadrupole Ion Trap researches carried out in my laboratory and in collaboratIon with other laboratories. This account commences with the announcement, in 1983, of the first commercially available Ion Trap detector, manufactured by Finnigan MAT, and continues to the present day. Much of the Ion Trap mass spectrometry research that took place during the period following this announcement until 1994 has been discussed in detail in three volumes entitled Practical Aspects of Ion Trap Mass Spectrometry that were published in 1995. Except for those researches that impinged directly on our work during this period, no discussIon of the contents of these three volumes is repeated here. The Ion Trap literature from 1994 to the present has been reviewed selectively so as to convey to the reader the dynamic nature of Ion Trap mass spectrometry and the wide variety of its applicatIon.
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DeterminatIon of dioxins/furans and PCBs by Quadrupole Ion-Trap gas chromatography-mass spectrometry.
Mass Spectrometry Reviews, 2000Co-Authors: Jeffry B. Plomley, Mila Lauševic, Raymond E. MarchAbstract:The versatility and sensitivity of the Quadrupole Ion Trap tandem mass spectrometer has been applied to the determinatIon of polychlorodibenzo-p-dioxins (PCDDs) and polychlorodibenzofurans (PCDFs), and of polychlorinated biphenyls (PCBs). A brief introductIon to the theory of Ion confinement in a Quadrupole Ion Trap permits discussIon of Ion trajectory stability, mass-selective Ion ejectIon, the frequencies of Ion motIon, and the role of resonant excitatIon of Ion motIon. The tandem mass spectrometric examinatIon of PCDDs and PCDFs eluting and co-eluting from a gas chromatographic column is described. Illustrative examples are given of the analysis of field samples containing PCDDs and PCDFs. A comparison is presented of the performance of each of a Quadrupole Ion Trap tandem mass spectrometer, a triple stage Quadrupole mass spectrometer, and a sector instrument of relatively high mass resolutIon for the determinatIon of PCDDs and PCDFs. This comparison is made with respect to instrument tuning, calibratIon plots, detectIon limits, Ion signals at low concentratIon, relative response factors, IonizatIon cross-sectIons, and the examinatIon of field samples. The applicatIon of Quadrupole Ion Trap tandem mass spectrometry to the examinatIon of PCBs is focused upon those PCB congeners that have the greatest toxicity. 39 congeners of the total of 209 PCB congeners have been identified as having the greatest toxicities. Chemical IonizatIon has been used for the determinatIon of co-eluting congeners #77 and #110 where the toxicity of the former is much greater than that of the latter. An analytical protocol, based on the variatIon of molecular Ion fragmentatIon according to the degree (or absence) of chlorine ortho-substitutIon, has been proposed for distinguishing between toxic and nontoxic PCB congeners.
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A RETROSPECTIVE REVIEW OF THE DEVELOPMENT AND APPLICATIon OF THE Quadrupole Ion Trap PRIOR TO THE APPEARANCE OF COMMERCIAL INSTRUMENTS
International Journal of Mass Spectrometry, 1999Co-Authors: John F. J. Todd, Raymond E. MarchAbstract:An account is given of the developments in the theory, technology, and applicatIons of the Quistor in the time window defined broadly as the 1970s and up to the appearance of commercial Quadrupole Ion Trap devices. The circumstances that drew the authors to pursue their research are described.
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Quadrupole Ion Trap mass spectrometry: theory, simulatIon, recent developments and applicatIons
Rapid Communications in Mass Spectrometry, 1998Co-Authors: Raymond E. MarchAbstract:This paper is a presentatIon of recent key developments in Quadrupole Ion Trap mass spectrometry. These key developments have been made in three areas; namely, the Trapping of Ions generated externally to the Ion Trap, the fine control of the trajectories of Ions confined within the Ion Trap, and the ejectIon of Ions from the Ion Trap. ApplicatIons of Quadrupole Ion Trap mass spectrometry that are illustrative of these developments are discussed. The origin of the Quadrupole Ion Trap and its mode of current usage are discussed briefly. © 1998 John Wiley & Sons, Ltd.
Scott A. Mcluckey - One of the best experts on this subject based on the ideXlab platform.
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Dynamic range extensIon in glow discharge Quadrupole Ion Trap mass spectrometry
Analytical Chemistry, 2002Co-Authors: Douglas C. Duckworth, Christopher M. Barshick, David H. Smith, Scott A. McluckeyAbstract:Methods of extending the dynamic range of the Quadrupole Ion Trap have been investigated by utilizing Ions generated from a radio frequency powered glow discharge. The success of the glow discharge Quadrupole Ion Trap technique for inorganic analysis is largely dependent upon increasing the dynamic range. The dynamic range has been increased to 10[sup 5] by selective accumulatIon methods which isolate Ions over a small mass regIon of interest. To accumulate selectively Ions of interest, static and dynamic electric fields were applied so that, as all Ions were gated into the Trap, only the Ions of interest were retained. Selective accumulatIon methods employed include mass-selective instability, single-frequency resonance ejectIon, combinatIon rf-dc, and entrance end cap dc. These methods, capable of being used alone or in combinatIon, were evaluated with respect to Ion-Trapping efficiency and linearity of signal response with respect to the injectIon period. Linear injectIon curves were obtained, and the ability to couple sequential selective Ion accumulatIon methods into a multiple ramp scan functIon for multielement quantificatIon was demonstrated. 28 refs., 8 figs.
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THERMAL DISSOCIATIon IN THE Quadrupole Ion Trap : IonS DERIVED FROM LEUCINE ENKEPHALIN
International Journal of Mass Spectrometry, 1999Co-Authors: K.g. Asano, Douglas E. Goeringer, Scott A. McluckeyAbstract:Abstract Rates of dissociatIon of protonated leucine enkephalin and the b 4 + fragment Ion derived from protonated leucine enkephalin have been measured as a functIon of helium bath gas temperature in a Quadrupole Ion Trap. DissociatIon rates were observed to be insensitive to the amplitude of the Trapping voltage over the range of values studied. This observatIon, along with theoretical arguments based on predicted levels of “rf heating,” indicates that any internal excitatIon of the Ions due to Ion Trap storage is minimal. The bath gas temperature can therefore be used to characterize the internal temperatures of the Ions. This approximatIon is expected to be most valid for high mass Ions and low mass bath gases, such as helium. ActivatIon parameters were obtained from Arrhenius plots of the rate data, and master equatIon modeling of the activatIon, deactivatIon, and dissociatIon processes was performed to provide an indicatIon as to how closely these Ions approached high-pressure limit behavior. Protonated leucine enkephalin more closely approached the high-pressure limit than the b 4 + Ion due to its larger size and the fact that the activatIon parameters were derived from somewhat lower dissociatIon rates. These studies suggest that the Quadrupole Ion Trap operated in the presence of a light, heated bath gas can be used to obtain Arrhenius activatIon parameters from the dissociatIon kinetics of relatively high mass Ions.
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Ion Remeasurement in the Radio Frequency Quadrupole Ion Trap
Analytical Chemistry, 1995Co-Authors: Douglas E. Goeringer, Richard I. Crutcher, Scott A. McluckeyAbstract:Multiple remeasurement of the same populatIon of stored Ions in a radio frequency (rf) Quadrupole Ion Trap is demonstrated. As the secular frequency of stored Ions is swept across a fixed-frequency resonance excitatIon signal via amplitude modulatIon of the confining rf voltage, the image current generated by the resulting coherent Ion motIon is measured simultaneously with tuned-circuit, phase-sensitive detectIon. Judicious selectIon of the resonance excitatIon frequency and rf voltage ramp limits enables the excitatIon-detectIon process to be performed over a range of mass-to-charge values. Furthermore, the inherent focusing of the Quadrupole field and use of helium buffer gas (nearly 10{sup -4} Torr) enable repeated scans to be made with negligible Ion loss. For a collectIon of C{sub 3}F{sub 5}{sup +} Ions (m/z 131) produced via a single electron IonizatIon event, the remeasurement efficiency during 24 scans, as judged by the scan-to-scan loss in signal, was > 99%. 33 refs., 3 figs.
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AccumulatIon and storage of Ionized duplex DNA molecules in a Quadrupole Ion Trap.
Analytical Chemistry, 1994Co-Authors: Mitchel J. Doktycz, Sohrab Habibi-goudarzi, Scott A. McluckeyAbstract:Evidence for the accumulatIon and storage of Ionized duplex DNA molecules in a Quadrupole Ion Trap is presented. Aqueous solutIons of complementary single-strand molecules of DNA were annealed to form duplexes in solutIon and subjected to electrospray IonizatIon. The Ions liberated in this process were transported through an atmosphere/vacuum interface and injected into a Quadrupole Ion Trap operated with a bath gas present at a pressure of 1 mTorr. Despite the roughly 2 order of magnitude poorer signal levels noted for electrospray of aqueous solutIons relative to those observed for single-strand oligonucleotides in methanol solutIons, aqueous solutIons were used to avoid denaturing the duplexes. Ion Trap mass spectra are reported here for duplexes consisting of two complementary 20-mer single strands and two complementary 10-mers. Tandem mass spectrometry results are also reported for the 10-mer duplex. These results are significant in that they indicate that the Ions are kinetically stable under the Ion injectIon, storage, and mass analysis conditIons of the Quadrupole Ion Trap operated with a relatively high pressure of bath gas. The tools of Ion Trap mass spectrometry can therefore be applied to this important class of compounds. 49 refs., 7 figs.
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Protonated water and protonated methanol cluster decompositIons in a Quadrupole Ion Trap
International Journal of Mass Spectrometry and Ion Processes, 1991Co-Authors: Scott A. Mcluckey, Gary L. Glish, K.g. Asano, J.e. BartmessAbstract:Abstract Electrospray mass spectra of water and methanol have been studied with a Quadrupole Ion Trap operated with background gas pressures of 2 × 10 −5 −2 × 10 −3 Torr. In each case, the most abundant Ions observed consist of protonated clusters of varying size, e.g. (H 2 O) n H + in which n ranges up into the twenties. For clusters of n > 6 or so, rapid desolvatIon is observed. For intermediate values of n , the desolvatIon rate constants can be readily measured in the typical time frame of a Quadrupole Ion Trap experiment. The internal temperature of the cluster Ions can be estimated from the known thermochemical parameters and the measured decompositIon rate constants. In all cases, the temperature exceeds that of the bath gas but is significantly less than 1000 K. It is also noted that the Ion temperature is inversely proportIonal to the logarithm of the bath gas pressure.
