Linewidth Pressure Measurement: A New Technique for High Vacuum Characterization

Jones, Chad A.; Dearden, David V.

doi:10.1007/s13361-014-1031-8

Cited by 8 publications

(17 citation statements)

References 27 publications

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“…In fact, variable-energy CRAFTI experiments conducted with monoatomic ions [9], which cannot dissociate, and with a few of the protonated amino acids (data not shown) do show decreasing cross sections with increasing kinetic energies. As a reviewer points out, collisions resulting in dissociation should already be included in the hard sphere momentum transfer cross section and so should not cause CRAFTI cross sections to be larger than IMS momentum transfer cross sections.…”

Section: Disagreement Of Absolute Crafti Cross Sections With Those Frmentioning

confidence: 94%

“…These two methods give slightly different absolute peak-to-peak voltages, but exhibit excellent linear correlation with each other (R 2 > 0.99). Absolute pressures were measured by measuring Ar + linewidths in Ar background gas as described in detail elsewhere [9]. Briefly, the linewidth of Ar + in neutral Ar was measured for each of the pulsed leak valve pressurization durations.…”

Section: Methodsmentioning

confidence: 99%

“…Ar + in Ar momentum transfer cross sections from the literature [17] enable calculation of the absolute pressure from the measured linewidths. Pressures measured in this way [9] are calibrated for Ar and so are not subject to uncertainty from chemical sensitivity, and are measured in the trapping cell so are not subject to errors resulting from measurement at a point remote from the trapping cell. They do not involve ion current measurements, so are not adversely affected by the magnetic field.…”

Section: Methodsmentioning

confidence: 99%

“…Steady-state pressures obtained with the pulsed leak system were varied by varying the length of time the pressurization solenoid valve was left open (while the evacuation solenoid was left closed). The operation and performance characteristics of our pulsed leak valve have been described in more detail elsewhere [9].…”

Section: Instrumentationmentioning

confidence: 99%

“…We have therefore converted the reported mobilities of the protonated amino acids to collision cross sections for comparison with measured CRAFTI cross sections, which can now be determined more accurately and with greater precision because of a new innovation for measuring pressures in the FTICR trapping cell [9]. We also report momentum transfer cross sections calculated from molecular modeling, and compare the computational results with the experimentally measured values to extract structural insights about the protonated amino acids.…”

mentioning

confidence: 99%

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Collision Cross Sections for 20 Protonated Amino Acids: Fourier Transform Ion Cyclotron Resonance and Ion Mobility Results

Anupriya

Jones

Dearden

2016

J. Am. Soc. Mass Spectrom.

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Abstract. We report relative dephasing cross sections for the 20 biogenic protonated amino acids measured using the cross sectional areas by Fourier transform ion cyclotron resonance (CRAFTI) technique at 1.9 keV in the laboratory reference frame, as well as momentum transfer cross sections for the same ions computed from Boltzmann-weighted structures determined using molecular mechanics. Cross sections generally increase with increasing molecular weight. Cross sections for aliphatic and aromatic protonated amino acids are larger than the average trend, suggesting these side chains do not fold efficiently. Sulfur-containing protonated amino acids have smaller than average cross sections, reflecting the mass of the S atom. Protonated amino acids that can internally hydrogen-bond have smaller than average cross sections, reflecting more extensive folding. The CRAFTI measurements correlate well with results from drift ion mobility (IMS) and traveling wave ion mobility (TWIMS) spectrometric measurements; CRAFTI results correlate with IMS values approximately as well as IMS and TWIMS values from independent measurements correlate with each other. Both CRAFTI and IMS results correlate well with the computed momentum transfer cross sections, suggesting both techniques provide accurate molecular structural information. Absolute values obtained using the various methods differ significantly; in the case of CRAFTI, this may be due to errors in measurements of collision gas pressure, measurement of excitation voltage, and/or dependence of cross sections on kinetic energy.

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Section: Disagreement Of Absolute Crafti Cross Sections With Those Frmentioning

confidence: 94%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Instrumentationmentioning

confidence: 99%

mentioning

confidence: 99%

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Collision Cross Sections for 20 Protonated Amino Acids: Fourier Transform Ion Cyclotron Resonance and Ion Mobility Results

Anupriya

Jones

Dearden

2016

J. Am. Soc. Mass Spectrom.

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Quantitative Collision Cross-Sections from FTICR Linewidth Measurements: Improvements in Theory and Experiment

Anupriya

Gustafson

Mortensen

et al. 2017

J. Am. Soc. Mass Spectrom.

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Two corrections to the equation used in the cross-sectional areas by Fourier transform ion cyclotron resonance ("CRAFTI") technique are identified. In CRAFTI, ion collision cross-sections are obtained from the pressure-dependent ion linewidths in Fourier transform mass spectra. The effects of these corrections on the accuracy of the cross-sections obtained using the CRAFTI technique are evaluated experimentally using the 20 biogenic amino acids and several crown ether complexes with protonated alkyl monoamines. Good absolute agreement is obtained between the CRAFTI cross-sections and the corresponding cross-sections obtained using both static drift ion mobility spectrometry and computational simulations. These results indicate that the CRAFTI cross-sections obtained using the updated equation presented here are quantitatively descriptive of the size and shape of the gas-phase ions. Cross-sections that differ by less than 3% are measured for the isobaric isomers n-butylamine and tert-butylamine complexed with the crown ethers. This level of precision is similar to what has been achieved previously using traveling wave ion mobility devices. These results indicate that CRAFTI can be used to probe subtle structural differences between ions with approximately the same precision as that achieved in traveling wave ion mobility devices. Graphical Abstract ᅟ.

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Advancing Orbitrap Measurements of Collision Cross Sections to Multiple Species for Broad Applications

et al. 2022

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Measurement of collision cross section (CCS), a parameter reflecting an ion’s size and shape, alongside high-resolution mass analysis extends the depth of molecular analysis by providing structural information beyond molecular mass alone. Although these measurements are most commonly undertaken using a dedicated ion mobility cell coupled to a mass spectrometer, alternative methods have emerged to extract CCSs directly by analysis of the decay rates of either time-domain transient signals or the FWHM of frequency domain peaks in FT mass analyzers. This information is also accessible from FTMS mass spectra obtained in commonly used workflows directly without the explicit access to transient or complex Fourier spectra. Previously, these experiments required isolation of individual charge states of ions prior to CCS analysis, limiting throughput. Here we advance Orbitrap CCS measurements to more users and applications by determining CCSs from commonly available mass spectra files as well as estimating CCS for multiple charge states simultaneously and showcase these methods by the measurement of CCSs of fragment ions produced from collisional activation of proteins.

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Linewidth Pressure Measurement: A New Technique for High Vacuum Characterization

Cited by 8 publications

References 27 publications

Collision Cross Sections for 20 Protonated Amino Acids: Fourier Transform Ion Cyclotron Resonance and Ion Mobility Results

Collision Cross Sections for 20 Protonated Amino Acids: Fourier Transform Ion Cyclotron Resonance and Ion Mobility Results

Quantitative Collision Cross-Sections from FTICR Linewidth Measurements: Improvements in Theory and Experiment

Advancing Orbitrap Measurements of Collision Cross Sections to Multiple Species for Broad Applications

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