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Roesch GC, Garand E. Tandem Mass-Selective Cryogenic Digital Ion Traps for Enhanced Cluster Formation. J Phys Chem A 2023; 127:7665-7672. [PMID: 37656038 DOI: 10.1021/acs.jpca.3c04706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
We present the implementation of tandem mass-selective cryogenic ion traps, designed to enhance the range of ion processing capabilities that can be performed prior to spectroscopic interrogation. We show that both the formation of ion clusters and mass filtering steps can be combined in a single cryogenic linear quadrupole ion trap driven by RF square waves. Mass filtering and mass isolation can be achieved by manipulation of the RF frequency and duty cycle. Very importantly, this scheme circumvents the need for high-amplitude RF voltages that can be incompatible with typical cryogenic ion processing conditions. In addition, proper adjustment of the stability boundaries during the clustering process allows for the preferential formation of a specific cluster size rather than a broad distribution of sizes. Lastly, we show that a specific cluster size can be formed, mass-selected, and then transferred to another ion trap for a second completely separate ion processing step. The instrumentation and modular design developed here expand the scope of ionic species and clusters that can be accessed by processing electrosprayed ions.
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Affiliation(s)
- Gina C Roesch
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave, Madison, Wisconsin 53706, United States
| | - Etienne Garand
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave, Madison, Wisconsin 53706, United States
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2
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Kregel SJ, Thompson BJ, Nathanson GM, Bertram TH. The Wisconsin Oscillator: A Low-Cost Circuit for Powering Ion Guides, Funnels, and Traps. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:2821-2826. [PMID: 34730958 DOI: 10.1021/jasms.1c00247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In this work, we present the Wisconsin Oscillator, a small, inexpensive, low-power circuit for powering ion-guiding devices such as multipole ion guides, ion funnels, active ion-mobility devices, and non-mass-selective ion traps. The circuit can be constructed for under $30 and produces two antiphase RF waveforms of up to 250 Vp-p in the high kilohertz to low megahertz range while drawing less than 1 W of power. The output amplitude is determined by a 0-6.5 VDC drive voltage, and voltage amplification is achieved using a resonant LC circuit, negating the need for a large RF transformer. The Wisconsin Oscillator automatically oscillates with maximum amplitude at the resonant frequency defined by the onboard capacitors, inductors, and the capacitive load of the ion-guiding device. We show that our circuit can replace larger and more expensive RF power supplies without degradation of the ion signal and expect this circuit to be of use in miniature and portable mass spectrometers as well as in home-built systems utilizing ion-guiding devices.
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Affiliation(s)
- Steven J Kregel
- Department of Chemistry, University of Wisconsin─Madison, 1101 University Ave, Madison, Wisconsin 53706, United States
| | - Blaise J Thompson
- Department of Chemistry, University of Wisconsin─Madison, 1101 University Ave, Madison, Wisconsin 53706, United States
| | - Gilbert M Nathanson
- Department of Chemistry, University of Wisconsin─Madison, 1101 University Ave, Madison, Wisconsin 53706, United States
| | - Timothy H Bertram
- Department of Chemistry, University of Wisconsin─Madison, 1101 University Ave, Madison, Wisconsin 53706, United States
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Lin JL, Chu ML, Chen CH. A portable multiple ionization source biological mass spectrometer. Analyst 2020; 145:3495-3504. [PMID: 32186555 DOI: 10.1039/d0an00126k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the past, matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI), used for large biomolecule detection, were usually installed in two separate mass spectrometers. In this study, they were equipped in the same mass spectrometer. This portable biological mass spectrometer has multiple ionization capabilities in the same mass spectrometer and shares the same mass analyzer and detector. This mass spectrometer can be operated under low vacuum (∼10-3 Torr) and can use air as the buffer gas. Therefore, the demand for pumping is reduced and rare gas feeding is no longer essential. A small scroll pump, employed to assist a miniature turbo pump, is sufficient to maintain the operational pressure. The mass spectra of biomolecules were obtained using frequency scanning instead of voltage ramping. Therefore, a wider mass-to-charge ratio (m/z) range was achieved. Furthermore, the design also couples a conversion dynode with a channeltron to enhance the mass detection range. This homemade mass spectrometer has the capability to measure charged particles with very large m/z values (m/z > 100 000). The concentrations of the studied compounds (angiotensin, insulin, cytochrome C, bovine serum albumin (BSA), immunoglobulin G, and immunoglobulin A) are from 5 femtomole to 100 picomole, and the mass resolutions are from 30 to 260. The mass range of this portable mass spectrometer was comparable with a commercial linear time-of-flight mass spectrometer owing to the use of the frequency scan.
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Affiliation(s)
- Jung-Lee Lin
- Genomics Research Center, Academia Sinica, Taipei, Taiwan.
| | - Ming-Lee Chu
- Institute of physics, Academia Sinica, Taipei, Taiwan
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4
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Marsh BM, Voss JM, Garand E. A dual cryogenic ion trap spectrometer for the formation and characterization of solvated ionic clusters. J Chem Phys 2015; 143:204201. [DOI: 10.1063/1.4936360] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Brett M. Marsh
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA
| | - Jonathan M. Voss
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA
| | - Etienne Garand
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA
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Marsh BM, Zhou J, Garand E. Vibrational Spectroscopy of Small Hydrated CuOH+ Clusters. J Phys Chem A 2014; 118:2063-71. [DOI: 10.1021/jp411614t] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Brett M. Marsh
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Jia Zhou
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Etienne Garand
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
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6
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Zekavat B, Szulejko JE, LaBrecque D, Olaitan AD, Solouki T. Efficient injection of low-mass ions into high magnetic field Fourier transform ion cyclotron resonance mass spectrometers. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:230-238. [PMID: 24338971 DOI: 10.1002/rcm.6768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 10/14/2013] [Accepted: 10/15/2013] [Indexed: 06/03/2023]
Abstract
RATIONALE Low-mass cut-off restrictions for injecting ions from external ion sources into high magnetic fields impose limitations for wide mass range analyses with Fourier transform ion cyclotron resonance (FTICR) instruments. Radio-frequency (RF)-only quadrupole ion guides (QIGs) with higher frequencies can be used to overcome low-mass cut-off in FTICR instruments. METHODS RF signals (1.0 MHz to 10.0 MHz) were applied to QIGs to transfer externally generated ions from either electron ionization (EI) or electrospray ionization (ESI) sources into ICR cells of 9.4 T FTICR mass spectrometers. Efficiencies of QIGs were evaluated using externally generated ions from: EI of acetone, air, and perfluorotributylamine mixture, EI of gas chromatography (GC)-separated components of a standard sample mixture, and ESI of complex mixtures such as petroleum and fulvic acid samples. RESULTS We were able to transfer ions with m/z as low as 26 from an external EI source into the ICR cell of a 9.4 T FTICR mass spectrometer and extend the operational low-mass range for ESI-FTICR analyses. High mass resolving power and mass measurement accuracy of GC/FTICR mass spectrometry were utilized to discriminate between oxygenated and non-oxygenated compounds in a 'Grob' sample. Ion losses based on SIMION ion trajectory predictions were consistent with experimental findings. CONCLUSIONS We demonstrated that the use of high-frequency QIGs can extend the operational lower m/z range for both external EI- and ESI-FTICR mass spectrometers. By considering both ICR and Mathieu equations of motions to describe ion trajectories, theoretical ion ejection thresholds (consistent with our experimental findings) could be predicted.
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Affiliation(s)
- Behrooz Zekavat
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76706, USA
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7
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Marmillod P, Antonioni S, Lorenz UJ. A radio frequency/high voltage pulse generator for the operation of a planar multipole ion trap/time-of-flight mass spectrometer. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:044707. [PMID: 23635220 DOI: 10.1063/1.4802630] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We present a radio frequency (RF)/high voltage pulse generator designed to provide suitable waveforms for the operation of a planar multipole ion trap/time-of-flight mass spectrometer. Our generator supplies a RF signal to two pairs of trapping electrodes, allowing ions to be stored in between them. Subsequently, the RF is rapidly switched off and high voltage extraction pulses are applied to the trap electrodes in order to obtain a time-of-flight spectrum of the stored ions. The quenching of the RF and the extraction pulses are synchronized to the RF phase, ensuring well-defined ejection conditions.
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Affiliation(s)
- Philippe Marmillod
- Centre de Recherches en Physique des Plasmas, École Polytechnique Fédérale de Lausanne (EPFL), Association EURATOM-Confédération Suisse, CH-1015 Lausanne, Switzerland.
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Kamrath MZ, Garand E, Jordan PA, Leavitt CM, Wolk AB, Van Stipdonk MJ, Miller SJ, Johnson MA. Vibrational characterization of simple peptides using cryogenic infrared photodissociation of H2-tagged, mass-selected ions. J Am Chem Soc 2011; 133:6440-8. [PMID: 21449591 PMCID: PMC3099397 DOI: 10.1021/ja200849g] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We present infrared photodissociation spectra of two protonated peptides that are cooled in a ~10 K quadrupole ion trap and "tagged" with weakly bound H(2) molecules. Spectra are recorded over the range of 600-4300 cm(-1) using a table-top laser source, and are shown to result from one-photon absorption events. This arrangement is demonstrated to recover sharp (Δν ~6 cm(-1)) transitions throughout the fingerprint region, despite the very high density of vibrational states in this energy range. The fundamentals associated with all of the signature N-H and C=O stretching bands are completely resolved. To address the site-specificity of the C=O stretches near 1800 cm(-1), we incorporated one (13)C into the tripeptide. The labeling affects only one line in the complex spectrum, indicating that each C=O oscillator contributes a single distinct band, effectively "reporting" its local chemical environment. For both peptides, analysis of the resulting band patterns indicates that only one isomeric form is generated upon cooling the ions initially at room temperature into the H(2) tagging regime.
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Affiliation(s)
- Michael Z. Kamrath
- Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, CT 06520 USA
| | - Etienne Garand
- Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, CT 06520 USA
| | - Peter A. Jordan
- Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, CT 06520 USA
| | - Christopher M. Leavitt
- Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, CT 06520 USA
| | - Arron B. Wolk
- Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, CT 06520 USA
| | | | - Scott J. Miller
- Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, CT 06520 USA
| | - Mark A. Johnson
- Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, CT 06520 USA
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Jau YY, Benito FM, Partner H, Schwindt PDD. Low power high-performance radio frequency oscillator for driving ion traps. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2011; 82:023118. [PMID: 21361584 DOI: 10.1063/1.3558569] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report a simple, efficient, high voltage radio frequency (RF) generator powered by a single voltage source (1.5-7 V) to resonantly drive ion traps or other capacitive loads. Our circuit is able to deliver RF voltages > 500 V(p-p) at frequencies ranging from 0.1 to 10 MHz. This RF oscillator uses low-cost, commercially available components, and can be easily assembled onto a circuit board of a few cm(2). Because of its simplicity and good efficiency, this circuit is useful in applications requiring small size and low power consumption such as portable ion trap systems where the duration of operation under battery power is of concern.
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Affiliation(s)
- Y-Y Jau
- Sandia National Laboratories, Albuquerque, New Mexico 87123, USA.
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10
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Berkout VD. Fragmentation of singly protonated peptides via interaction with metastable rare gas atoms. Anal Chem 2009; 81:725-31. [PMID: 19099409 DOI: 10.1021/ac802214e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The effects of metastable energy level and peptide sequence on the fragmentation patterns of singly charged peptide ions dissociated in collisions with metastable rare gas atoms were studied. Fragmentation spectra of singly charged peptide ions were shown to be more structure-informative and very different from those obtained in low-energy collision-induced dissociation. Unusual odd-electron radical a- and x-ions were observed. Several fragment ions corresponding to a side-chain loss were also observed, which allowed differentiation between leucine and isoleucine. The fragmentation mechanism depends on electronic energy transferred during interaction with metastable gas atoms and proceeds either via Penning ionization with formation of radical odd-electron doubly charged molecular cation or via high-energy excitation of internal degrees of freedom of the peptide cation.
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Aizikov K, Mathur R, O'Connor PB. The spontaneous loss of coherence catastrophe in Fourier transform ion cyclotron resonance mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2009; 20:247-56. [PMID: 19013078 PMCID: PMC2872030 DOI: 10.1016/j.jasms.2008.09.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 09/29/2008] [Accepted: 09/29/2008] [Indexed: 05/16/2023]
Abstract
The spontaneous loss of coherence catastrophe (SLCC) is a frequently observed, yet poorly studied, space-charge related effect in Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS). This manuscript presents an application of the filter diagonalization method (FDM) in the analysis of this phenomenon. The temporal frequency behavior reproduced by frequency shift analysis using the FDM shows the complex nature of the SLCC, which can be explained by a combination of factors occurring concurrently, governed by electrostatics and ion packet trajectories inside the ICR cell.
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Affiliation(s)
- Konstantin Aizikov
- Cardiovascular Proteomics Center, Boston University School of Medicine, Boston, Massachusetts, USA
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12
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Mathur R, O'Connor PB. Artifacts in Fourier transform mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2009; 23:523-9. [PMID: 19142849 PMCID: PMC2872032 DOI: 10.1002/rcm.3904] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Recent work on a new, higher sensitivity preamplifier design for Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) revealed a number of artifact peaks (spectral features) which do not contain useful chemical information. In order to determine the cause of these artifacts and eliminate them, these severely distorted spectra were compared with similarly distorted signal models. The source of several common signal processing artifacts was thereby determined and correlated to radio-frequency interference (RFI) noise and saturation of the amplifier and/or the digitizer. Under such conditions, the fast Fourier transform (FFT) generates spectral artifact peaks corresponding to harmonics and mixing frequencies of the real signal peaks and RFI frequencies. While this study was done using FTICRMS data, it is important to stress that these artifacts are inherent to the digitization and FFT process and thus are relevant to any FT-based MS instrument, including the orbitrap and FT ion trap.
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Affiliation(s)
- Raman Mathur
- Department of Electrical and Computer Engineering, 8 St. Mary's St., Boston University, Boston, MA 02215, USA
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13
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Berkout VD, Doroshenko VM. Fragmentation of phosphorylated and singly charged peptide ions via interaction with metastable atoms. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2008; 278:150-157. [PMID: 19956340 PMCID: PMC2598758 DOI: 10.1016/j.ijms.2008.04.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Fragmentation of phosphorylated peptide ions via interaction with electronically excited metastable argon atoms was studied in a linear trap - time-of-flight mass spectrometer. Doubly charged ions of phosphorylated peptides from an Enolase digest were produced by electrospray ionization and subjected to a metastable atom beam in the linear trap. The metastable argon atoms were generated using a glow-discharge source. An intensive series of c- and z- ions were observed in all cases, with the phosphorylation group intact. The formation of molecular radical cations with reduced charge indicated that an electron transfer from a highly excited metastable state of argon to the peptide cation occurred. Additionally, singly charged Bradykinin, Substance P and Fibrinopeptide A molecular ions were fragmented via interaction with electronically excited metastable helium atoms. The fragmentation mechanism was different in this case and involved Penning ionization.
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Robbins MD, Yoon OK, Zuleta I, Barbula GK, Zare RN. Computer-controlled, variable-frequency power supply for driving multipole ion guides. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:034702. [PMID: 18377035 DOI: 10.1063/1.2884148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A high voltage, variable-frequency driver circuit for powering resonant multipole ion guides is presented. Two key features of this design are (1) the use of integrated circuits in the driver stage and (2) the use a stepper motor for tuning a large variable capacitor in the resonant stage. In the present configuration the available frequency range spans a factor of 2. The actual values of the minimum and maximum frequencies depend on the chosen inductor and the capacitance of the ion guide. Feedback allows for stabilized, computer-adjustable rf amplitudes over the range of 5-500 V. The rf power supply was characterized over the range of 350-750 kHz and evaluated by driving a quadrupole ion guide in an electrospray time-of-flight mass spectrometer.
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Affiliation(s)
- Matthew D Robbins
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA
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Lin C, Mathur R, Aizikov K, O'Connor PB. First signal on the cryogenic Fourier-transform ion cyclotron resonance mass spectrometer. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2007; 18:2090-3. [PMID: 17931882 PMCID: PMC2872035 DOI: 10.1016/j.jasms.2007.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Revised: 09/05/2007] [Accepted: 09/07/2007] [Indexed: 05/25/2023]
Abstract
The construction and achievement of the first signal on a cryogenic Fourier-transform ion cyclotron resonance mass spectrometer (FTICR-MS) are reported here, demonstrating proof-of-concept of this new instrument design. Building the FTICR cell into the cold bore of a superconducting magnet provided advantages over conventional warm bore design. At 4.2 K, the vacuum system cryopumps itself, thus removing the requirement for a large bore to achieve the desired pumping speed for maintaining base pressure. Furthermore, because the bore diameter has been reduced, the amount of magnet wire needed to achieve high field and homogeneity was also reduced, greatly decreasing the cost/Tesla of the magnet. The current instrument implements an actively shielded 14-Tesla magnet of vertical design with an external matrix-assisted laser desorption/ionization (MALDI) source. The first signal was obtained by detecting the laser desorbed/ionized (LDI) C(60)(+*) ions, with the magnet at 7 Tesla, unshimmed, and the preamplifier mounted outside of the vacuum chamber at room temperature. A subsequent experiment done with the magnet at 14 Tesla and properly shimmed produced a C(60) spectrum showing approximately 350,000 resolving power at m/z approximately 720. Increased magnetic field strength improves many FTMS performance parameters simultaneously, particularly mass resolving power and accuracy.
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Affiliation(s)
- Cheng Lin
- Cardiovascular Proteomics Center, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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Mathur R, Knepper RW, O'Connor PB. A low-noise, wideband preamplifier for a Fourier-transform ion cyclotron resonance mass spectrometer. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2007; 18:2233-41. [PMID: 18029195 PMCID: PMC2872042 DOI: 10.1016/j.jasms.2007.09.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Revised: 06/21/2007] [Accepted: 09/17/2007] [Indexed: 05/25/2023]
Abstract
FTMS performance parameters such as limits of detection, dynamic range, sensitivity, and even mass accuracy and resolution can be greatly improved by enhancing its detection circuit. An extended investigation of significant design considerations for optimal signal-to-noise ratio in an FTMS detection circuit are presented. A low noise amplifier for an FTMS is developed based on the discussed design rules. The amplifier has a gain of approximately 3500 and a bandwidth of 10 kHz to 1 MHz corresponding to m/z range of 100 Da to 10 kDa (at 7 Tesla). The performance of the amplifier was tested on a MALDI-FTMS, and has demonstrated a 25-fold reduction in noise in a mass spectrum of C(60) compared with that of a commercial amplifier.
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Affiliation(s)
- Raman Mathur
- Department of Electrical and Computer Engineering, 8 St. Mary's St., Boston University, Boston, MA. U.S.A. - 02215
- Cardiovascular Proteomics Center, 670 Albany St., Boston University, Boston, MA. U.S.A. - 02118
| | - Ronald W. Knepper
- Department of Electrical and Computer Engineering, 8 St. Mary's St., Boston University, Boston, MA. U.S.A. - 02215
| | - Peter B. O'Connor
- Department of Electrical and Computer Engineering, 8 St. Mary's St., Boston University, Boston, MA. U.S.A. - 02215
- Cardiovascular Proteomics Center, 670 Albany St., Boston University, Boston, MA. U.S.A. - 02118
- Mass Spectrometry Resource, Department of Biochemistry, 715 Albany St., Boston University, Boston, MA. U.S.A. - 02118
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Julian RR, Mabbett SR, Jarrold MF. Ion funnels for the masses: experiments and simulations with a simplified ion funnel. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2005; 16:1708-12. [PMID: 16095911 DOI: 10.1016/j.jasms.2005.06.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2005] [Revised: 06/21/2005] [Accepted: 06/22/2005] [Indexed: 05/03/2023]
Abstract
A modified ion funnel is described. Counterintuitively, increased spacing between electrodes results in enhanced "focusing" of the ions through the funnel. Consequently, the internal diameter (i.d.) of the funnel need not decrease to the conductance limit (as in previous designs). A simple dc-only lens, which also serves as the conductance limit, combined with the natural flow of gas is used to extract the ions from the funnel. Ions with mass to charge ratios varying between 75 and 3000 m/z are passed through the funnel with no apparent discrimination. The funnel can be operated under mild conditions that preserve weakly bound noncovalent complexes. After testing several designs, a thin closely spaced dc lens was found to be the best solution for extracting ions. A simple method for simulating ion trajectories at nonzero pressures based on ion mobility and explicit diffusion is described. This theoretical approach was used to design and calculate ion trajectories for the modified funnel presented here. Finally, the increased spacing between electrodes in the current funnel significantly relaxes machining constraints, reduces cost, and enhances ease of use versus previous funnel designs.
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Affiliation(s)
- Ryan R Julian
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.
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18
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O'Connor PB, Budnik BA, Ivleva VB, Kaur P, Moyer SC, Pittman JL, Costello CE. A high pressure matrix-assisted laser desorption ion source for Fourier transform mass spectrometry designed to accommodate large targets with diverse surfaces. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2004; 15:128-32. [PMID: 14698563 DOI: 10.1016/j.jasms.2003.10.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
A new design for a high pressure MALDI-FTMS instrument is described and initial data are shown. The instrument incorporates a large, 10 cm x 10 cm, sample translation stage to accommodate and position the MALDI target. The new instrument allows coupling to a wide variety of surface techniques such as gel electrophoresis or surface plasmon resonance. Coupling to thin layer chromatography is shown. Furthermore, a new nozzle design allows high pressure collisional cooling sufficient to stabilize gangliosides while minimizing the gas load on the system.
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Affiliation(s)
- Peter B O'Connor
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
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