Quadrature detection for the separation of the signals of positive and negative ions in fourier transform ion cyclotron resonance mass spectrometry

Schweikhard, L.; Drader, Jared J.; Shi, Stone D.-H.; Hendrickson, Christopher L.; Marshall, Alan G.

doi:10.1063/1.1454343

Cited by 4 publications

(3 citation statements)

References 11 publications

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“…In fact, FT ICR has measured the mass resolution of two peptides at a difference that is less than the mass of an electron or ∼0.0005 u . Furthermore, simultaneous measurements of C60+ and C60− have been made by FT-ICR MS to show the mass resolution within the mass of 2 electrons …”

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confidence: 99%

Measuring the Mass of an Electron by LC/TOF-MS: A Study of “Twin Ions”

Ferrer

Thurman

2005

Anal. Chem.

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While investigating the in-source CID fragmentation of nonsteroidal antiinflammatory drugs (NSAIDs), it was noticed that the same fragment ion (nominal mass) formed in either positive or negative ion electrospray for a suite of NSAIDs. For example, ibuprofen with a molecular mass of 206, fragments to the m/z 161 ion in negative ion from its deprotonated molecule (m/z 205, [M - H]-) and fragments to the m/z 161 ion in positive ion from its protonated molecule (m/z 207, [M + H]+). This fragment ion was euphemistically called a "twin ion"because of the same nominal mass despite opposite charge. The CID fragmentation of the twin ions was confirmed also by LC/MS/MS ion trap. Accurate mass measurements in negative ion show that the loss was due to CO2 (measured loss of 43.9897 atomic mass units (u) versus calculated loss of 43.9898 u for N = 10) and in positive ion the loss is due to HCOOH (measured loss of 46.0048 u versus calculated loss of 46.0055 u, N = 10). It was realized that, in fact, the ions were not "identical mass twins of opposite charge" but separated in accurate mass by two electrons. The accurate mass measurement by liquid chromatography/time-of-flight-mass spectrometry (LC/TOF-MS) can distinguish between the two fragment ions of ibuprofen (161.13362 +/- 0.00019 and 161.13243 +/- 0.00014 for N = 20). This experiment was repeated for two other NSAIDs, and the mass of an electron was measured as the difference between the twin ions, which was 0.00062 u +/- 14.8% relative standard deviation (N = 20 analyses). Thus, the use of continuous calibration makes it possible to measure the mass of an electron within one significant figure using the NSAID solution. This result shows the importance of including electron mass in accurate mass measurements and the value of a benchmark test for LC/TOF-MS mass accuracy.

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Measuring the Mass of an Electron by LC/TOF-MS: A Study of “Twin Ions”

Ferrer

Thurman

2005

Anal. Chem.

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“…Line broadening processes, such as ion-molecule collisions produce peak skirts that extend from one spectrum half to the other causing significant peak centroid shifts when the ion cyclotron frequencies are sufficiently low. This effect can be removed through the use of quadrature detection (Schweikhard et al, 2002), which detects the charge displacement as a circularly polarized signal.…”

Section: B Internal Mass Calibration and Calibration Practicementioning

confidence: 99%

Accurate mass measurements by Fourier transform mass spectrometry

Zhang¹,

Rempel

Pramanik³

et al. 2004

Mass Spectrometry Reviews

122

133

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The capability for accurate mass measurements is an important attribute of Fourier transform mass spectrometry (FTMS). Unlike other instrumental methods in mass spectrometry, FTMS still offers significant opportunities to improve mass measurement accuracy (MMA), making it an area of research. This review covers the published literature in FTMS from the late 1970s to the present. We discuss the development and evolution of mass calibration that give accuracies in the low ppm range. We sketch the derivation and show the common foundation of these mass calibration procedures. We also describe the relation of mass calibration and the fundamentals of ion motion and space-charge effects, and we review efforts to improve the basic calibration procedure particularly those that correct for effects of space charge. The advent of matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) have opened the door for FTMS to be used for analyzing at high performance biopolymers, including proteins, oligodeoxynucleotides (ODNs), oligosaccharides, and synthetic polymers. We also discuss the utility of FTMS for accurate mass measurement in these areas and some practical ways to improve MMA. # 2004 Wiley Periodicals, Inc., Mass Spec Rev 24:286-309, 2005

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“…Note that by "opposite polarities" we mean a phase shift of 180 degrees between the rf-signals. ("Quadrature excitation", where phase shifts of 90°, 180° and 270° are applied, 3,25,26 is not considered in this contribution.) only in a hyperbolical Penning trap, including the two-electrode trap, 27 for a trapping potential as accurate as possible, the parametric excitation has "perfect" geometry, as it is identical with the equipotential lines of the trapping electrodes.…”

Section: Theoretical Considerationsmentioning

confidence: 99%

Unintended Parametric Ejection of Ions from an Ion Cyclotron Resonance Trap by Two-Electrode Axialization

Martinez

Herlert

Marx

et al. 2009

Eur J Mass Spectrom (Chichester)

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Azimuthal quadrupolar excitation is a commonly used technique in the field of ion cyclotron resonance mass spectrometry, in particular in combination with buffer-gas collisions to achieve axialization of the stored ions. If the quadrupolar excitation is applied with only one phase to a set of two opposing ring segments (rather than the "regular" method where two sets of electrodes are addressed with opposite polarities), parametric resonance effects at the frequencies 2nu(z) and nu(p) = nu(+) - nu(-) can lead to unintended ejection of ions from the trap. These parametric resonances have been revisited both theoretically and experimentally: multipole components of different azimuthal excitation schemes are derived by a simple vector representation of the excitation signal applied to the ring segments. Thus, parametric contributions can be easily identified, as demonstrated for the two-electrode and the four-electrode quadrupolar excitation schemes as well as further examples. In addition, the effect of the single-phase two-electrode quadrupolar excitation is demonstrated for storage and axialization of cluster ions.

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Quadrature detection for the separation of the signals of positive and negative ions in fourier transform ion cyclotron resonance mass spectrometry

Cited by 4 publications

References 11 publications

Measuring the Mass of an Electron by LC/TOF-MS: A Study of “Twin Ions”

Measuring the Mass of an Electron by LC/TOF-MS: A Study of “Twin Ions”

Accurate mass measurements by Fourier transform mass spectrometry

Unintended Parametric Ejection of Ions from an Ion Cyclotron Resonance Trap by Two-Electrode Axialization

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