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EP-4403911-B1 - TANDEM DIFFERENTIAL MOBILITY ION MOBILITY SPECTROMETRY

EP4403911B1EP 4403911 B1EP4403911 B1EP 4403911B1EP-4403911-B1

Inventors

  • GARDNER, BEN D.
  • Eicemen, Gary A.
  • Fowler,Peter

Dates

Publication Date
20260506
Application Date
20240123

Claims (15)

  1. A method for identifying a chemical composition, comprising: collecting a chemical sample and introducing the chemical sample to a detection system (100); performing, with a differential mobility spectrometer (112), differential mobility spectrometry on the chemical sample to separate ions within the chemical sample into a first constituent group based on a first analysis characteristic, wherein performing differential mobility spectrometry on the chemical sample further comprises: filtering the ions within the ionized flow such that only ions having a desired mobility pass to a fragmenter (122); fragmenting the filtered sample to further dissociate ions within the filtered sample to generate additional ion types having distinctive mobility characteristics; performing, with an ion mobility spectrometer (114), ion mobility spectrometry on the first constituent group to separate ions within the first constituent group into a second constituent group based on a second analysis characteristic; determining an identity of the chemical sample based on ions present within the second constituent group; characterised by filtering, with a first shutter (140) of the ion mobility spectrometer (114) at an inlet of a first positive ion drift tube (136), the first constituent group entering the first positive ion drift tube based on ion mobility; filtering, with a second shutter (142) of the ion mobility spectrometer (114) at an inlet of a first negative ion drift tube (138), the first constituent group entering the first negative ion drift tube (138) based on ion mobility, providing, with the first and second shutters (140, 142), selected ions from the first constituent group to the first positive ion drift tube (136) and the first negative ion drift tube (138); and fragmenting, with a first fragmenter (144) of the ion mobility spectrometer (114) disposed at an outlet of the first positive ion drift tube (136) and a second fragmenter (146) of the ion mobility spectrometer (114) disposed at an outlet of the first negative ion drift tube (138), the selected ions from the first constituent group to further dissociate the selected ions from the first constituent group to generate the second constituent group with additional ion types having distinctive mobility characteristics.
  2. The method of claim 1, further comprising, ionizing the chemical sample using an ionization source (107) to produce an ionized flow (108) prior to performing differential mobility spectrometry on the chemical sample, and optionally wherein performing differential mobility spectrometry on the chemical sample further comprises: subjecting the ionized flow (108) to a first radio frequency field to cause ions within the ionized flow (108) to oscillate; and applying a first voltage differential across the first radio frequency field to cause positive ions within the ionized flow to drift towards a negative charge and negative ions to drift towards a positive charge to separate the positive ions from the negative ions within the ionized flow (108).
  3. The method of claim 2, wherein performing differential mobility spectrometry on the chemical sample further comprises: filtering the ions within the fragmented ionized flow to generate the first constituent group such that only the first constituent group passes to an ion mobility spectrometer (114) of the detection system, wherein applying the first voltage differential further includes, progressively modifying the first voltage differential to allow selected ions within the ionized flow and/or the fragmented ionized flow to pass into the ion mobility spectrometer (114) as the first constituent group; and generating a first data set for the first constituent group based on the first analysis characteristic.
  4. The method of claim 2, wherein performing differential mobility spectrometry on the chemical sample further comprises: applying a second voltage differential across a second radio frequency field to cause positive ions within the fragmented ionized flow to drift towards a negative charge and negative ions to drift towards a positive charge to separate the positive ions from the negative ions within the fragmented ionized flow; and filtering the ions within the fragmented ionized flow to generate the first constituent group such that only the first constituent group passes to an ion mobility spectrometer (114).
  5. The method of claim 4, wherein applying the first voltage differential and/or applying the second voltage differential further includes, progressively modifying the first voltage differential and/or the second voltage differential to allow selected ions within the ionized flow and/or the fragmented ionized flow to pass into the ion mobility spectrometer (114) as the first constituent group; and wherein performing differential mobility spectrometry further comprises, generating a first data set for the first constituent group based on the first analysis characteristic..
  6. The method of claim 5, wherein performing ion mobility spectrometry on the first constituent group further comprises: passing the ionized flow containing only the first constituent group to an analytical module of the ion mobility spectrometer (114); and applying a voltage differential across the analytical module to draw positive ions with in the first constituent group to a negative charge of a first analytical module of the ion mobility spectrometer (114) and draw the negative ions within the first constituent group to a positive charge of a second analytical module of the ion mobility spectrometer (114); separating the ions of first continued group in space and performing a first time of flight analysis on the ions within the first constituent group to allow selected ions within the first constituent group to pass to a fragmenter; and fragmenting the selected ions within the first constituent group to further dissociate and generate additional ion types having distinctive mobility characteristics generating a fragmented flow of ions forming the second constituent group, and optionally wherein performing ion mobility spectrometry on the first constituent group further comprises: performing a second time of flight analysis on the fragmented flow of ions within second constituent group to generate a second data set for the second constituent group based on the second analysis characteristic; correlating the second dataset generated for the second constituent group with the first dataset generated for the first constituent group; and determining the identity of the chemical composition based on the correlation between the first dataset and the second data set.
  7. A system (100), comprising: a chemical detector (102) including a chemical analyte inlet (104); an ionization module (106) having an ionization source (107) therein fluidly connected to the chemical analyte inlet (104) configured to receive the chemical analyte and ionize the chemical analyte to generate an ionized flow; and an analytical module (110) fluidly connected to the ionization module (106) to receive the ionized flow and configured to determine a chemical identity of the chemical analyte, the analytical module (110) including: a differential mobility spectrometer (112) fluidly connected to the chemical analyte inlet, wherein the differential mobility spectrometer (112) comprises, a first set of electrodes (116) including a first positively charged electrode (118) and a first negatively charged electrode (120) configured to separate positive ions from negative ions within the ionized flow and wherein only ions of a predetermined mobility characteristic flow past the first set of electrodes (116); and a fragmenter (122) downstream of the first set of electrodes (116) configured to fragment the filtered sample to further dissociate ions within the filtered sample to generate a fragmented ionized flow with additional ion types having distinctive mobility characteristics; and an ion mobility spectrometer (114) fluidly connected to the differential mobility spectrometer (112), characterised in that the ion mobility spectrometer (114) further comprises: a first shutter (140) at an inlet of a first positive ion drift tube (136) configured to filter a first constituent group entering the first positive ion drift tube (136) based on ion mobility; a second shutter (142) at an inlet of a first negative ion drift tube (138) configured to filter the first constituent group entering the first negative ion drift tube (138) based on ion mobility, wherein the first and second shutter (140,142) provide selected ions from the first constituent group to the first positive ion drift tube (136) and the first negative ion drift tube (138); and a first fragmenter (144) disposed at an outlet of the first positive ion drift tube (136) and a second fragmenter (146) disposed at an outlet of the first negative ion drift tube (138) configured to fragment the selected ions from the first constituent group to further dissociate the selected ions from the first constituent group to generate the second constituent group with additional ion types having distinctive mobility characteristics.
  8. The system of claim 7, wherein the ionization source (107) is configured to ionize the chemical analyte flowing through ionization region, and optionally wherein the ionization source (107) includes an electric-field ionizer, a radioactive ionizer, or a photo-ionizer.
  9. The system of claim 7 or 8, wherein an outlet of the fragmenter (122) is an outlet of the differential mobility spectrometer (112) such that the fragmented ionized flow forms the first constituent group and passes to the ion mobility spectrometer (114).
  10. The system of claim 7, 8 or 9, wherein the differential mobility spectrometer (112) comprises a second set of electrodes including a second positively charged electrode and a second negatively charged electrode downstream of the fragmenter (122) configured to separate positive ions from negative ions within the fragmented ionized flow and ions of a predetermined mobility flow past the second set of electrodes forming a first constituent group, wherein the first constituent group passes to the ion mobility spectrometer (114).
  11. The system of claim 10, wherein the differential mobility spectrometer (112) further comprises a computational module (132) configured to generate a first data set for the first constituent group based on a first analysis characteristic.
  12. The system of claim 11, wherein the ion mobility spectrometer (114) comprises: the first positive ion drift tube (136) and the first negative ion drift tube each fluidly connected to an outlet of the differential mobility spectrometer (112), wherein the first positive ion drift tube is configured to receive positive ions from the first constituent group and the first negative ion drift tube configured to receive negative ions from the first constituent group.
  13. The system of claim 9, wherein the ion mobility spectrometer (114) further comprises: a second positive ion drift tube (148) configured to receive fragmented ions from first fragmenter (144) and a second negative ion drift tube (150) configured to receive fragmented ions from the second fragmenter (146); a positive ion detector (152) at an end of the second positive ion drift tube (148) configured to draw the positive ions and towards the positive ion detector and configured to detect a time of flight of the positive ions of the second constituent group within the second positive ion drift tube; a negative ion detector (154) at an end of the second negative ion drift tube (150) configured to draw the negative ions towards the negative ion detector and configured to detect a time of flight of the negative ions of the second constituent group within the second negative ion drift tube.
  14. The system of claim 13, wherein the analytical module (102) is configured to determine a drift time of the positive ions of the second constituent group within the second positive ion drift tube (148) and a drift time of the negative ions of the second constituent group in the second negative ion drive tube (150) and generate a second data set for the second constituent group based on the second analysis characteristic.
  15. The system of claim 13, wherein the analytical module further comprises a computational module (156) configured to correlate the second dataset generated for the second constituent group with the first dataset generated for the first constituent group; and determine the identity of the chemical analyte based on the correlation between the first dataset and the second data set.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Application No. 63/440,454, filed January 23, 2023. TECHNICAL FIELD The present disclosure relates to differential mobility and ion mobility spectrometry, e.g., for chemical detection. BACKGROUND Mobility spectrometry is a means for determining a chemical identity of an analyte. In the field of remote, unattended chemical sensing, the conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved systems and methods for chemical detection that provides higher accuracy with respect to identifying more constituents of the sample, while at the same time providing higher resolution results as compared to prior system. This disclosure provides a solution for this need. US 2022/397552 A1 discloses a molecular identification using field induced fragmentation spectra by reactive stage tandem differential mobility spectrometry. SUMMARY A method for identifying a chemical composition is provided as defined by claim 1. The method can further include, ionizing the chemical sample using an ionization source to produce an ionized flow prior to performing differential mobility spectrometry on the chemical sample. Performing differential mobility spectrometry on the chemical sample can further include, subjecting the ionized flow to a first radio frequency field to cause ions within the ionized flow to oscillate, and applying a first voltage differential across the first radio frequency field to cause positive ions within the ionized flow to drift towards a negative charge and negative ions to drift towards a positive charge to separate the positive ions from the negative ions within the ionized flow. In certain embodiments, performing differential mobility spectrometry on the chemical sample further includes, filtering the ions within the fragmented ionized flow to generate the first constituent group such that only the first constituent group passes to an ion mobility spectrometer of the detection system. Applying the first voltage differential can include, progressively modifying the first voltage differential to allow selected ions within the ionized flow and/or the fragmented ionized flow to pass into the ion mobility spectrometer as the first constituent group. The method can include, generating a first data set for the first constituent group based on the first analysis characteristic. In certain embodiments, performing differential mobility spectrometry on the chemical sample further includes, applying a second voltage differential across a second radio frequency field to cause positive ions within the fragmented ionized flow to drift towards a negative charge and negative ions to drift towards a positive charge to separate the positive ions from the negative ions within the fragmented ionized flow. In certain such embodiments, differential mobility spectrometry can further include filtering the ions within the fragmented ionized flow to generate the first constituent group such that only the first constituent group passes to an ion mobility spectrometer. Applying the first voltage differential and/or applying the second voltage differential further includes, progressively modifying the first voltage differential and/or the second voltage differential to allow selected ions within the ionized flow and/or the fragmented ionized flow to pass into the ion mobility spectrometer as the first constituent group, and wherein performing differential mobility spectrometry further comprises, generating a first data set for the first constituent group based on the first analysis characteristic. Performing ion mobility spectrometry on the first constituent group can further include, passing the ionized flow containing only the first constituent group to an analytical module the ion mobility spectrometer, and applying a voltage differential across the analytical module to draw positive ions with in the first constituent group to a negative charge of a first analytical module of the ion mobility spectrometer and draw the negative ions within the first constituent group to a positive charge of a second analytical module of the ion mobility spectrometer. Performing ion mobility spectrometry on the first constituent group can further include, separating the ions of first continued group in space and performing a first time of flight analysis on the ions within the first constituent group to allow selected ions within the first constituent group to pass to a fragmenter, and fragmenting the selected ions within the first constituent group to further dissociate and generate additional ion types having distinctive mobility characteristics generating a fragmented flow of ions forming the second constituent group. Performing ion mobility spectrometry on the first constituent group can further include, performing a second time of flight analysis on the fra