Ion mobility spectrometry: A personal view of its development at UCSB

Bowers, Michael T.

doi:10.1016/j.ijms.2014.06.016

Cited by 46 publications

(42 citation statements)

References 130 publications

(149 reference statements)

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“…Figure 1 shows the positive ion mass spectra for four laboratory-generated particle types selected for their distinct spectral profiles: (a) Regal black, (b) premixed ethylene flame soot generated with a fuel equivalence ratio (f) of 2, (c) Nano-C fullerene black, and (d) C 60 (buckminsterfullerene). The number of carbon atoms comprising C n C in each mass spectrum are separated into three basic categories (low carbon: C 1 C to C 5 C , mid carbon: C 6 C to C 29 C , and fullerenes: C 30 C /C 60 2C to C 166 C ), which may be related to the stable structures of C n C ions (i.e., linear, rings, and fullerenes) as indicated at the top of Figure 1 (Bowers 2014).…”

Section: Positive Carbon Ion Mass Spectramentioning

confidence: 99%

“…In the mass spectra shown in Figure 1, the mass spacing for the dominant C n C ion signals below C 30 C is 12 m/z (C 1 ), whereas the spacing for dominant carbon ion signals above C 30 C is 24 m/z (C 2 ). This spacing change may represent a transition from carbon clusters with open 1D and 2D structures (e.g., linear chains, monocyclic and polycyclic rings) to closed or hollow 3D, geodesic structures (Rohlfing et al 1984;Bloomfield et al 1985;von Helden et al 1993;Handschuh et al 1995;Bowers 2014).…”

Section: Sp-ams Carbon Ion Distributionsmentioning

confidence: 99%

“…At the other extreme, thermally treated and laser-heated BC contains moreordered graphitic structures (Oberlin 1984;Vander Wal and Jensen 1998), which are correspondingly less reactive (Schmid et al 2011). Environmentally relevant BC samples produced by diesel engines, aircraft turbines, or biomass burning exhibit a wide range of chemical structures, which may aid in the identification of ambient soot sources (Vander Wal et al 2010, 2014. This range of chemical and physical properties, which depends upon the efficiency of combustion, affects the BC optical properties and has been described as soot "maturity" (L opez-Yglesias et al 2014).…”

Section: Introductionmentioning

confidence: 99%

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Investigations of SP-AMS Carbon Ion Distributions as a Function of Refractory Black Carbon Particle Type

Onasch

Fortner

Trimborn³

et al. 2015

Aerosol Science and Technology

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The soot particle aerosol mass spectrometer (SP-AMS) instrument combines continuous wave laser vaporization with electron ionization aerosol mass spectrometry to characterize airborne, refractory black carbon (rBC) particles. The laser selectively vaporizes absorbing rBC-containing particles, allowing the SP-AMS to provide direct chemical information on the refractory and non-refractory chemical components, providing the potential to fingerprint various rBC particle types. In this study, SP-AMS mass spectra were measured for 12 types of rBC particles produced by industrial and combustion processes to explore differences in the carbon cluster (C n C ) mass spectra. The C n C mass spectra were classified into three categories based on their ion distributions, which varied with rBC particle type. The carbon ion distributions were investigated as a function of laser power, electron ionization (on/off), and ion charge (positive or negative). Results indicate that the dominant positive ion-formation mechanism is likely the vaporization of small, neutral carbon clusters followed by electron ionization (C 1 C to C 5 C ). Significant ion signal from larger carbon cluster ions (and their fragment ions in the small carbon cluster range), including mid carbon (C 6 C to C 29 C ) and fullerene (greater than C 30 C ) ions, were observed in soot produced under incomplete combustion conditions, including biomass burning, as well as in fullerene-enriched materials. Fullerene ions were also observed at high laser power with electron ionization turned off, formed via an additional ionization mechanism. We expect this SP-AMS technique to find application in the identification of the source and atmospheric history of airborne ambient rBC particles.

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Section: Positive Carbon Ion Mass Spectramentioning

confidence: 99%

Section: Sp-ams Carbon Ion Distributionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigations of SP-AMS Carbon Ion Distributions as a Function of Refractory Black Carbon Particle Type

Onasch

Fortner

Trimborn³

et al. 2015

Aerosol Science and Technology

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“…The challenge is to decipher structural information from ion mobility experiments. [7][8][9] The physical quantity characterizing the shape is the collision cross section (CCS), [10] which will be introduced in more detail in the Section on Ion mobility and collision cross sections. The present tutorial clarifies how to interpret CCS measurements in terms of three-dimensional structure for ions larger than 100 atoms extracted from the solution by electrospray ionization (ESI).…”

Section: Introductionmentioning

confidence: 99%

Linking molecular models with ion mobility experiments. Illustration with a rigid nucleic acid structure

D’Atri¹,

Porrini²,

Rosu³

et al. 2015

J. Mass Spectrom.

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Ion mobility spectrometry experiments allow the mass spectrometrist to determine an ion's rotationally averaged collision cross section Ω EXP . Molecular modelling is used to visualize what ion three-dimensional structure(s) is(are) compatible with the experiment. The collision cross sections of candidate molecular models have to be calculated, and the resulting Ω CALC are compared with the experimental data. Researchers who want to apply this strategy to a new type of molecule face many questions: (1) What experimental error is associated with Ω EXP determination, and how to estimate it (in particular when using a calibration for traveling wave ion guides)? (2) How to generate plausible 3D models in the gas phase? (3) Different collision cross section calculation models exist, which have been developed for other analytes than mine. Which one(s) can I apply to my systems? To apply ion mobility spectrometry to nucleic acid structural characterization, we explored each of these questions using a rigid structure which we know is preserved in the gas phase: the tetramolecular G-quadruplex [dTGGGGT] 4 , and we will present these detailed investigation in this tutorial. Additional supporting information may be found in the online version of this article at the publisher's web site.Keywords: ion mobility spectrometry; collision cross section; structure; nucleic acids; simulations; molecular modeling; gas-phase ion structure IntroductionElectrospray mass spectrometry (ESI-MS) in native conditions can preserve the structures of biomolecules and separate them according to their mass-to-charge ratios. [1,2] Ion mobility spectrometry (IMS) separates ions according to their size-to-charge ratios in the gas-phase. [3][4][5][6] Size is related to the mass (or number of atoms) and to the three-dimensional shape of a molecule. Therefore, by hyphenating IMS to mass spectrometry (IM-MS), one can sort ions according to both mass and shape. The challenge is to decipher structural information from ion mobility experiments. [7][8][9] The physical quantity characterizing the shape is the collision cross section (CCS), [10] which will be introduced in more detail in the Section on Ion mobility and collision cross sections. The present tutorial clarifies how to interpret CCS measurements in terms of three-dimensional structure for ions larger than 100 atoms extracted from the solution by electrospray ionization (ESI). The gold standard is to match CCSs experimentally obtained from IMS with CCSs calculated for modelling three-dimensional structures of the ion of interest. We will discuss the factors that can affect the precision (reproducibility) and accuracy in both the measurements and the calculations. Understanding each of these factors is crucial to interpret quantitative matches confidently and assess the meaningfulness of structural assignments.On the experimental side, we will describe the determination of CCS from traveling wave ion mobility spectrometers and from drift tube ion mobility spectrometers, with example data recorde...

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“…The ion-mobility method is well established [14,15]. Experiments were performed on an in-house constructed drifttube ion mobility-mass spectrometer (IM-MS) similar to one described previously [12,16].…”

Section: Ion Mobility Spectrometrymentioning

confidence: 99%

From Compact to String—The Role of Secondary and Tertiary Structure in Charge-Induced Unzipping of Gas-Phase Proteins

Warnke

Hoffmann

Seo

et al. 2016

J. Am. Soc. Mass Spectrom.

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In the gas phase, protein ions can adopt a broad range of structures, which have been investigated extensively in the past using ion mobility-mass spectrometry (IM-MS) based methods. Compact ions with low number of charges undergo a Coulomb-driven transition to partially folded species when the charge increases and finally form extended structures with presumably little or no defined structure when the charge state is high. However, with respect to the secondary structure, IM-MS methods are essentially blind. Infrared (IR) spectroscopy, on the other hand, is sensitive to such structural details and there is increasing evidence that helices as well as β-sheet-like structures can exist in the gas phase, especially for ions in low charge states. Very recently, we showed that also the fully extended form of highly charged protein ions can adopt a distinct type of secondary structure that features a characteristic C5-type hydrogen bond pattern. Here we use a combination of IM-MS and IR spectroscopy to further investigate the influence of the initial, native conformation on the formation of these structures. Our results indicate that when intramolecular Coulomb-repulsion is large enough to overcome the stabilization energies of the genuine secondary structure, all proteins, regardless of their sequence or native conformation, form C5-type hydrogen bond structures. Furthermore, our results suggest that in highly charged proteins the positioning of charges along the sequence is only marginally influenced by the basicity of individual residues.In the gas-phase environment of a mass spectrometer, proteins can adopt a broad range of distinct structures. When electrosprayed from native, buffered solutions especially large proteins and protein complexes are known to retain features of their condensed-phase conformation -a fact that found broad application in the field of native mass spec-

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Ion mobility spectrometry: A personal view of its development at UCSB

Cited by 46 publications

References 130 publications

Investigations of SP-AMS Carbon Ion Distributions as a Function of Refractory Black Carbon Particle Type

Investigations of SP-AMS Carbon Ion Distributions as a Function of Refractory Black Carbon Particle Type

Linking molecular models with ion mobility experiments. Illustration with a rigid nucleic acid structure

From Compact to String—The Role of Secondary and Tertiary Structure in Charge-Induced Unzipping of Gas-Phase Proteins

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