A Miniaturized Fourier Transform Electrostatic Linear Ion Trap Mass Spectrometer: Mass Range and Resolution

Johnson, Joshua T.; Lee, Kenneth W.; Bhanot, Jay S.; McLuckey, Scott A.

doi:10.1007/s13361-018-02126-x

Cited by 13 publications

(9 citation statements)

References 33 publications

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“…Two configurations have been employed: multireflectron time-of-flight where the ions exit the trap for detection [58][59][60]62 and an approach where a ring detector is used to pick up the induced charge from the oscillating ion bunch. [55][56][57]61 In both cases, very high m/z resolving powers, in excess of 100 000, have been reported. 55,58−60 Such high m/z resolving powers have not yet been achieved in CDMS, partly because the design considerations for these two applications are different.…”

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confidence: 93%

“…In addition to applications in CDMS, ELITs have been employed as conventional mass spectrometers where the m / z ratios are determined. − In this application, bunches of ions are injected into the trap, and the signal intensity reflects the number of charges in the bunch rather than the charge of single ions. Two configurations have been employed: multireflectron time-of-flight where the ions exit the trap for detection − , and an approach where a ring detector is used to pick up the induced charge from the oscillating ion bunch. − , In both cases, very high m / z resolving powers, in excess of 100 000, have been reported. ,− Such high m / z resolving powers have not yet been achieved in CDMS, partly because the design considerations for these two applications are different. In CDMS, the ELITs are designed for efficient trapping so that single ions can be trapped for long times and the charge can be determined accurately.…”

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confidence: 99%

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Higher Resolution Charge Detection Mass Spectrometry

et al. 2020

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Charge detection mass spectrometry is a single particle technique where the masses of individual ions are determined from simultaneous measurements of each ion’s m/z ratio and charge. The ions pass through a conducting cylinder, and the charge induced on the cylinder is detected. The cylinder is usually placed inside an electrostatic linear ion trap so that the ions oscillate back and forth through the cylinder. The resulting time domain signal is analyzed by fast Fourier transformation; the oscillation frequency yields the m/z, and the charge is determined from the magnitudes. The mass resolving power depends on the uncertainties in both quantities. In previous work, the mass resolving power was modest, around 30–40. In this work we report around an order of magnitude improvement. The improvement was achieved by coupling high-accuracy charge measurements (obtained with dynamic calibration) with higher resolution m/z measurements. The performance was benchmarked by monitoring the assembly of the hepatitis B virus (HBV) capsid. The HBV capsid assembly reaction can result in a heterogeneous mixture of intermediates extending from the capsid protein dimer to the icosahedral T = 4 capsid with 120 dimers. Intermediates of all possible sizes were resolved, as well as some overgrown species. Despite the improved mass resolving power, the measured peak widths are still dominated by instrumental resolution. Heterogeneity makes only a small contribution. Resonances were observed in some of the m/z spectra. They result from ions with different masses and charges having similar m/z values. Analogous resonances are expected whenever the sample is a heterogeneous mixture assembled from a common building block.

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Higher Resolution Charge Detection Mass Spectrometry

et al. 2020

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“…Consider an ion of mass m , with isotopologue spacing of 1 Da. The frequency with which adjacent isotopologues will overlap in the ELIT (i.e., the beat frequency of the pair of ions) is given by the difference in the fundamental oscillation frequencies of the two ions, as indicated in eq , where c is the frequency-to-mass calibration for the ELIT Similarly, the beat frequency between m and its isotopologue 2 Da away is given by The ratio of beat periods, given by the inverse of the ratio of beat frequencies, is shown by eq : If m is large compared with the Δ m (2 or 1 in this case), the term approaches 1, whereas approaches 2.…”

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Simultaneous Isolation of Nonadjacent m/z Ions Using Mirror Switching in an Electrostatic Linear Ion Trap

et al. 2019

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Simultaneous isolation of ions of disparate mass-to-charge (m/z) ratios is demonstrated via appropriately timed pulsing of entrance and exit ion mirrors in an electrostatic linear ion trap (ELIT) mass spectrometer. Manipulation of the voltages of the entrance and exit mirrors, referred to as “mirror switching”, has been demonstrated as a method in which ions can be both captured and isolated. High resolution isolation (>35 000) was previously demonstrated by selective gating of trapping electrodes to avoid ion lapping while closely spaced ions could continue to separate [Anal. Chem.2019918789]. In this work, we demonstrate that advantage can be taken of the ion lapping phenomenon in an ELIT to enable the simultaneous isolation of ions of disparate m/z ratios using mirror switching. This process is demonstrated with minimal ion loss using isotopologues of three carborane compounds ranging in m/z from 320 to 1020. Simultaneous isolation is demonstrated with the isolation of two and three peaks in separate isotopic distributions as well as with the isolation of alternating isotopologues within the same distribution. Such simultaneous isolation experiments are particularly useful when conducting experiments in which a mass calibrant is needed or when multiplexing in a tandem MS workflow.

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“…CDMS is a technique where the mass is determined for individual nano- or microparticles in a sample. CDMS analysis has allowed the characterization of high-mass and heterogeneous samples including amyloid fibrils, , DNA, , peptides, polymerase chain reaction products, proteins, − synthetic polymers, − and viruses. − …”

Section: Introductionmentioning

confidence: 99%

Accurately Mapping Image Charge and Calibrating Ion Velocity in Charge Detection Mass Spectrometry

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Murray

Caldwell

et al. 2020

J. Am. Soc. Mass Spectrom.

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Image charge detection is the foundation of charge detection mass spectrometry (CDMS). The mass-to-charge ratio, m/z, of a highly charged ion or particle is determined by measuring the particle's charge and velocity. Charge is typically determined from a calibrated image charge signal, and the particle velocity is calculated using the peaks from the shaped signal as they relate to the particle position and time-of-flight through a detector of known length. Although much has been done to improve the charge accuracy in CDMS, little has been done to address the inconsistencies in the particle velocity measurements and the interpretation of peak position and effective electrode length. In this work, we combine SIMION ion trajectory software and the Shockley−Ramo theorem to accurately determine the effective electrode length, peak position, and shape of the signal peaks. Six model charge detector geometries were examined with this method and evaluated in laboratory experiments. Experimental results in all cases agreed with the simulations. Using a charge detector with multiple, 12.7 mm-long cylindrical electrodes, experimental velocities across and between electrodes agreed within 0.25% relative standard deviation (RSD) when this method was used to correct for effective electrode lengths, corresponding to an uncertainty in the effective electrode length of only 40 μm. For a detector with multiple electrodes and varied electrode spacing, experiments showed that the peak amplitude and shape vary with the geometry and with the particle path through the detector, whereas all peak areas agreed to within 2.3% RSD. For a charge detector made of two printed circuit boards, the velocities agreed within 0.44% RSD using the calculated effective electrode length.

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A Miniaturized Fourier Transform Electrostatic Linear Ion Trap Mass Spectrometer: Mass Range and Resolution

Cited by 13 publications

References 33 publications

Higher Resolution Charge Detection Mass Spectrometry

Higher Resolution Charge Detection Mass Spectrometry

Simultaneous Isolation of Nonadjacent m/z Ions Using Mirror Switching in an Electrostatic Linear Ion Trap

Accurately Mapping Image Charge and Calibrating Ion Velocity in Charge Detection Mass Spectrometry

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