Prediction of a Space Charge Induced Upper Molecular Mass Limit Towards Achieving Unit Mass Resolution in Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Mitchell, Dale W.; Smith, Richard D.

doi:10.1002/(sici)1096-9888(199607)31:7<771::aid-jms357>3.0.co;2-#

Cited by 53 publications

(45 citation statements)

References 35 publications

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“…Another possible and related mechanism may be associated to the phase-locking phenomenon [26,27]. Although considered mostly for two different ion species of close m/z, the same phenomenon is responsible for the long term coherence (ion cloud stability) of ions of the same m/z.…”

Section: Correction For the Frequency Shiftsmentioning

confidence: 99%

Mass measurement errors caused by “local” frequency perturbations in FTICR mass spectrometry

Masselon

Tolmachev

Anderson

et al. 2002

J. Am. Soc. Mass Spectrom.

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102

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One of the key qualities of mass spectrometric measurements for biomolecules is the mass measurement accuracy (MMA) obtained. FTICR presently provides the highest MMA over a broad m/z range. However, due to space charge effects, the achievable MMA crucially depends on the number of ions trapped in the ICR cell for a measurement. Thus, beyond some point, as the effective sensitivity and dynamic range of a measurement increase, MMA tends to decrease. While analyzing deviations from the commonly used calibration law in FTICR we have found systematic errors which are not accounted for by a "global" space charge correction approach. The analysis of these errors and their dependence on charge population and post-excite radius have led us to conclude that each ion cloud experiences a different interaction with other ion clouds. We propose a novel calibration function which is shown to provide an improvement in MMA for all the spectra studied. (J Am Soc Mass Spectrom 2002, 13, 99 -106)

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Section: Correction For the Frequency Shiftsmentioning

confidence: 99%

Mass measurement errors caused by “local” frequency perturbations in FTICR mass spectrometry

Masselon

Tolmachev

Anderson

et al. 2002

J. Am. Soc. Mass Spectrom.

Self Cite

102

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“…The dynamics of single particles inside the FTICR trap was analyzed by many groups in both the FTICR and physics communities. [1][2][3][4][5][6][7][8] The FTICR community has been interested mainly in obtaining a calibration formula, which connects measured frequency with ion mass. 9 The early studies investigated the effects of various external fields and ion-neutral collisions on single particle trajectories.…”

mentioning

confidence: 99%

“…Simple 2D simulation programs have been used by different groups to investigate various phenomena related to coulombic interactions in FTICR. 3,4,[29][30][31] The first attempt to implement coulombic interaction in realistic three-dimensional (3D) calculations of simulations involving a relatively small number of interacting particles was undertaken by the groups of Inoue and Nikolaev. They developed a 3D parallel code to integrate the equations of motion of up to 1024 interacting particles for 50 000 time-steps.…”

mentioning

confidence: 99%

Realistic modeling of ion cloud motion in a Fourier transform ion cyclotron resonance cell by use of a particle‐in‐cell approach

Nikolaev

Heeren

Popov

et al. 2007

Rapid Comm Mass Spectrometry

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Using a 'Particle-In-Cell' approach taken from plasma physics we have developed a new threedimensional (3D) parallel computer code that today yields the highest possible accuracy of ion trajectory calculations in electromagnetic fields. This approach incorporates coulombic ion-ion and ion-image charge interactions into the calculation. The accuracy is achieved through the implementation of an improved algorithm (the so-called Boris algorithm) that mathematically eliminates cyclotron motion in a magnetic field from digital equations for ion motion dynamics. It facilitates the calculation of the cyclotron motion without numerical errors. At every time-step in the simulation the electric potential inside the cell is calculated by direct solution of Poisson's equation. Calculations are performed on a computational grid with up to 128 T 128 T 128 nodes using a fast Fourier transform algorithm. The ion populations in these simulations ranged from 1000 up to 1 000 000 ions. A maximum of 3 000 000 time-steps were employed in the ion trajectory calculations. This corresponds to an experimental detection time-scale of seconds. In addition to the ion trajectories integral time-domain signals and mass spectra were calculated. The phenomena observed include phase locking of particular m/z ions (high-resolution regime) inside larger ion clouds. A focus was placed on behavior of a cloud of ions of a single m/z value to understand the nature of Fourier transform ion cyclotron resonance (FTICR) resolution and mass accuracy in selected ion mode detection. The behavior of two and three ion clouds of different but close m/z was investigated as well. Peak coalescence effects were observed in both cases. Very complicated ion cloud dynamics in the case of three ion clouds was demonstrated. It was found that magnetic field does not influence phase locking for a cloud of ions of a single m/z. The ion cloud evolution time-scale is inversely proportional to magnetic field. The number of ions needed for peak coalescence depends quadratically on the magnetic field. Copyright # 2007 John Wiley & Sons, Ltd.The leading role Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) plays in biological mass spectrometry is directly related to its unsurpassed resolution and mass accuracy combined with the possibility of utilizing all known ionization and fragmentation methods. Further improvement of mass accuracy will be greatly facilitated by a more detailed understanding of the motion of ions during ion introduction into the FTICR cell, excitation of their cyclotron motion, fragmentation and detection of induced signal. Starting from the early days of FTICR-MS the theory of ion motion in the ICR cell was an important research topic in this field. The dynamics of single particles inside the FTICR trap was analyzed by many groups in both the FTICR and physics communities. [1][2][3][4][5][6][7][8] The FTICR community has been interested mainly in obtaining a calibration formula, which connects measured frequency with ion mass. 9 The e...

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“…At a large radial or axial distance from the center of the ICR cell the rapid periodic cyclotron and axial motions of a single ion time-average spatial nonidealities in the electric and magnetic fields [18]. However, these same nonidealities also disrupt the ion motion of a coherent ion packet, increasing the rate of signal decay [19]. There are a number of trap configurations that have been proposed or tested to decrease these nonidealities [20 -25].…”

mentioning

confidence: 99%

“…This produces a dispersion of ions along the z-axis of the ICR cell. This will result in a change in the observed cyclotron frequency based on ion axial position and/or rapid dephasing of the ion cloud [6,19,33,34]. Therefore, scan-to-scan variation of ion kinetic energy will change the observed cyclotron frequency and also should cause nonlinear calibration errors.…”

mentioning

confidence: 99%

Reduction of axial kinetic energy induced perturbations on observed cyclotron frequency

Kaiser

Weisbrod

Webb

et al. 2008

J. Am. Soc. Mass Spectrom.

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With Fourier transform ion cyclotron resonance (FTICR) mass spectrometry one determines the mass-to-charge ratio of an ion by measuring its cyclotron frequency. However, the need to confine ions to the trapping region of the ion cyclotron resonance (ICR) cell with electric fields induces deviations from the unperturbed cyclotron frequency. Additional perturbations to the observed cyclotron frequency are often attributed to changes in space charge conditions. This study presents a detailed investigation of the observed ion cyclotron frequency as a function of ion z-axis kinetic energy. In a perfect three-dimensional quadrupolar field, cyclotron frequency is independent of position within the trap. However, in most ICR cell designs, this ideality is approximated only near the trap center and deviations arise from this ideal quadrupolar field as the ion moves both radially and axially from the center of the trap. To allow differentiation between deviations in observed cyclotron frequency caused from changes in space charge conditions or differences in oscillation amplitude, ions with identical molecular weights but different axial kinetic energy, and thus amplitude of z-axis motion, were simultaneously trapped within the ICR cell. This allows one to attribute deviations in observed cyclotron frequency to differences in the average force from the radial electric field experienced by ions of different axial amplitude. Experimentally derived magnetron frequency is compared with the magnetron frequency calculated using SIMION 7.0 for ions of different axial amplitude. Electron promoted ion coherence, or EPIC, is used to reduce the differences in radial electric fields at different axial positions. Thus with the application of EPIC, the differences in observed cyclotron frequencies are minimized for ions of different axial oscillation amplitudes. [1,2] has become the ideal mass analyzer for the analysis of multiply charged ions produced by electrospray ionization with its ability to provide high-resolution and accurate mass measurements. It has become common practice to couple electrospray ionization to liquid chromatography for online analysis of complex mixtures with FTICRmass spectrometry (MS) [3][4][5]. To effectively sample the chromatographic peaks as they elute from the column, a short duty cycle is needed. However, with ion cyclotron resonance (ICR) mass spectrometers, the achievable mass resolving power, sensitivity, and mass measurement accuracy decrease with shorter acquisition time periods. Therefore, the majority of the time ions spent in the ICR cell is used for detection and not on some form of ion manipulation event such as ion accumulation, ion focusing, or ion selection. To meet the demand for high-throughput analysis while utilizing the high performance that FTICR mass spectrometers offer, ions are usually accumulated external to the magnetic field and then trapped in the ICR cell with some variation of gated trapping [3, 6 -8]. Hybrid instruments allow for ion selection and fragmentation to take pla...

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Prediction of a Space Charge Induced Upper Molecular Mass Limit Towards Achieving Unit Mass Resolution in Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Cited by 53 publications

References 35 publications

Mass measurement errors caused by “local” frequency perturbations in FTICR mass spectrometry

Mass measurement errors caused by “local” frequency perturbations in FTICR mass spectrometry

Realistic modeling of ion cloud motion in a Fourier transform ion cyclotron resonance cell by use of a particle‐in‐cell approach

Reduction of axial kinetic energy induced perturbations on observed cyclotron frequency

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