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Title: Method and apparatus for ion mobility spectrometry with alignment of dipole direction (IMS-ADD)

Abstract

Techniques and instrumentation are described for analyses of substances, including complex samples/mixtures that require separation prior to characterization of individual components. A method is disclosed for separation of ion mixtures and identification of ions, including protein and other macromolecular ions and their different structural isomers. Analyte ions are not free to rotate during the separation, but are substantially oriented with respect to the drift direction. Alignment is achieved by applying, at a particular angle to the drift field, a much stronger alternating electric field that "locks" the ion dipoles with moments exceeding a certain value. That value depends on the buffer gas composition, pressure, and temperature, but may be as low as .about.3 Debye under certain conditions. The presently disclosed method measures the direction-specific cross-sections that provide the structural information complementing that obtained from known methods, and, when coupled to those methods, increases the total peak capacity and specificity of gas-phase separations. Simultaneous 2-D separations by direction-specific cross sections along and orthogonally to the ion dipole direction are also possible.

Inventors:
 [1];  [1];  [1]
  1. Richland, WA
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA
Sponsoring Org.:
USDOE
OSTI Identifier:
902910
Patent Number(s):
7,170,053
Application Number:
11/097,855
Assignee:
Battelle Memorial Institute (Richland, WA) BMI
DOE Contract Number:
AC06-76RL01830
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION

Citation Formats

Shvartsburg, Alexandre A, Tang, Keqi, and Smith, Richard D. Method and apparatus for ion mobility spectrometry with alignment of dipole direction (IMS-ADD). United States: N. p., 2007. Web.
Shvartsburg, Alexandre A, Tang, Keqi, & Smith, Richard D. Method and apparatus for ion mobility spectrometry with alignment of dipole direction (IMS-ADD). United States.
Shvartsburg, Alexandre A, Tang, Keqi, and Smith, Richard D. Tue . "Method and apparatus for ion mobility spectrometry with alignment of dipole direction (IMS-ADD)". United States. doi:. https://www.osti.gov/servlets/purl/902910.
@article{osti_902910,
title = {Method and apparatus for ion mobility spectrometry with alignment of dipole direction (IMS-ADD)},
author = {Shvartsburg, Alexandre A and Tang, Keqi and Smith, Richard D},
abstractNote = {Techniques and instrumentation are described for analyses of substances, including complex samples/mixtures that require separation prior to characterization of individual components. A method is disclosed for separation of ion mixtures and identification of ions, including protein and other macromolecular ions and their different structural isomers. Analyte ions are not free to rotate during the separation, but are substantially oriented with respect to the drift direction. Alignment is achieved by applying, at a particular angle to the drift field, a much stronger alternating electric field that "locks" the ion dipoles with moments exceeding a certain value. That value depends on the buffer gas composition, pressure, and temperature, but may be as low as .about.3 Debye under certain conditions. The presently disclosed method measures the direction-specific cross-sections that provide the structural information complementing that obtained from known methods, and, when coupled to those methods, increases the total peak capacity and specificity of gas-phase separations. Simultaneous 2-D separations by direction-specific cross sections along and orthogonally to the ion dipole direction are also possible.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Jan 30 00:00:00 EST 2007},
month = {Tue Jan 30 00:00:00 EST 2007}
}

Patent:

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  • Approaches to characterization and separation of ions involving their mobilities in gases were developed since 1960-s. Conventional ion mobility spectrometry (IMS) measures the absolute mobility and the field asymmetric waveform IMS (FAIMS) exploits the difference between mobilities at high and low electric fields. However, all previous work was based on the orientationally averaged cross-sections Ωavg between ions and buffer gas molecules. Virtually all large ions are electric dipoles that will be oriented by a sufficiently strong electric field. At typical FAIMS conditions, that must happen for dipole moments > ~400 Debye, found for many macroions including most proteins above ~30more » kDa. Mobilities of aligned dipoles depend on directional cross-sections Ωdir (rather than Ωavg), which should have a major effect on FAIMS separation parameters. Here we study the FAIMS behavior of ESI-generated ions for ten proteins up to ~70 kDa. Those above 29 kDa exhibit a strong increase of mobility at high field, which is consistent with predicted ion dipole alignment. This effect expands the FAIMS peak capacity by an order of magnitude, allowing separation of up to ~102 distinct protein conformers and revealing information about Ωdir and ion dipole moment that is of potential utility for structural characterization. Possible means to extend the dipole alignment to smaller ions are discussed.« less
  • Ion mobility spectrometer apparatus may include an ion interface that is operable to hold positive and negative ions and to simultaneously release positive and negative ions through respective positive and negative ion ports. A first drift chamber is operatively associated with the positive ion port of the ion interface and encloses an electric field therein. A first ion detector operatively associated with the first drift chamber detects positive ions from the first drift chamber. A second drift chamber is operatively associated with the negative ion port of the ion interface and encloses an electric field therein. A second ion detectormore » operatively associated with the second drift chamber detects negative ions from said second drift chamber.« less
  • An ion mobility detector has dual drift regions respectively on either side of a centrally located reaction region and respectively separated therefrom by dual shutter grids. Each drift region terminates in a Faraday cup. An ion accelerating electrical field gradient is provided between the Faraday cups so that negative ions are drawn into one drift region and positively charged ions are drawn into the other drift region.
  • Disclosed are a device and method for improved interfacing of differential mobility spectrometry (DMS) or field asymmetric waveform ion mobility spectrometry (FAIMS) analyzers of substantially planar geometry to subsequent or preceding instrument stages. Interfacing is achieved using curved DMS elements, where a thick ion beam emitted by planar DMS analyzers or injected into them for ion filtering is compressed to the gap median by DMS ion focusing effect in a spatially inhomogeneous electric field. Resulting thinner beams are more effectively transmitted through necessarily constrained conductance limit apertures to subsequent instrument stages operated at a pressure lower than DMS, and/or moremore » effectively injected into planar DMS analyzers. The technology is synergetic with slit apertures, slit aperture/ion funnels, and high-pressure ion funnel interfaces known in the art which allow for increasing cross-sectional area of MS inlets. The invention may be used in integrated analytical platforms, including, e.g., DMS/MS, LC/DMS/MS, and DMS/IMS/MS that could replace and/or enhance current LC/MS methods, e.g., for proteomics research.« less
  • We report the first evaluation of a platform coupling a high speed field asymmetric ion mobility spectrometry microchip (µFAIMS) with drift tube ion mobility and mass spectrometry (IMS-MS). The µFAIMS/IMS-MS platform was used to analyze biological samples and simultaneously acquire multidimensional information of detected features from the measured FAIMS compensation fields and IMS drift times, while also obtaining accurate ion masses. These separations thereby increase the overall separation power, resulting increased information content, and provide more complete characterization of more complex samples. The separation conditions were optimized for sensitivity and resolving power by the selection of gas compositions and pressuresmore » in the FAIMS and IMS separation stages. The resulting performance provided three dimensional separations, benefitting both broad complex mixture studies and targeted analyses by e.g. improving isomeric separations and allowing detection of species obscured by “chemical noise” and other interfering peaks.« less