Real-time detection method and system for identifying individual aerosol particles

• US 6,959,248 B2
• Filed: 10/24/2002
• Issued: 10/25/2005
• Est. Priority Date: 10/25/2001
• Status: Active Grant

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Fergenson, David Philip, Gard, Eric Evan
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Barbee, Manuel L.
• Application Number:
  US10/280,608
• Publication Number:
  US 20040024539A1
• Time in Patent Office: 1,097 Days
• Field of Search: 702/19, 702 22- 32, 250/281, 250/285, 250/286, 250/288, 436/173
• US Class Current: 702/22
• CPC Class Codes: G01N 15/0205 by optical means
• CPC Class Codes: G01N 15/10 Investigating individual particles
• CPC Class Codes: G01N 2001/2223 aerosol sampling devices
• CPC Class Codes: H01J 49/0036 Step by step routines describing the handling of the data generated during a measurement
• CPC Class Codes: H01J 49/0095 Particular arrangements for generating, introducing or analyzing both positive and negative analyte ions ion/ion reactions H01J49/0072
• CPC Class Codes: H01J 49/0445 with means for introducing as a spray, a jet or an aerosol electrospray ion sources H01J49/165
• CPC Class Codes: H01J 49/10 Ion sources; Ion guns

Abstract

A method and system of identifying individual aerosol particles in real time. Sample aerosol particles are compared against and identified with substantially matching known particle types by producing positive and negative test spectra of an individual aerosol particle using a bipolar single particle mass spectrometer. Each test spectrum is compared to spectra of the same respective polarity in a database of predetermined positive and negative spectra for known particle types and a set of substantially matching spectra is obtained. Finally the identity of the individual aerosol particle is determined from the set of substantially matching spectra by determining a best matching one of the known particle types having both a substantially matching positive spectrum and a substantially matching negative spectrum associated with the best matching known particle type.

Claims

1. A method of identifying individual aerosol particles in real time comprising:

receiving sample aerosol particles;

producing positive and negative test spectra of an individual aerosol particle using a bipolar single particle mass spectrometer;

comparing each test spectrum to spectra of the same respective polarity in a database of predetermined positive and negative spectra for known particle types to obtain a set of substantially matching spectra; and

determining the identity of the individual aerosol particle from the set of substantially matching spectra by determining a best matching one of the known particle types having both a substantially matching positive spectrum and a substantially matching negative spectrum associated therewith from the set.

2. The method as in claim 1,

wherein the comparison of each test spectrum to spectra of the same respective polarity in the database produces a similarity score for each predetermined spectrum, with the set of substantially matching spectra based on a predetermined similarity score threshold.

3. The method as in claim 2,

wherein the best matching one of the known particle types has associated therewith, for at least one of the substantially matching positive and negative spectra, the highest order similarity score of all substantially matching spectra of the same respective polarity.

4. The method as in claim 2,

wherein the comparison of each test spectrum to the database includes converting each test spectrum into a corresponding test spectrum vector, and vector multiplying the test spectrum vector with a transpose of a predetermined spectrum vector of the same respective polarity to calculate the similarity score.

5. The method as in claim 1,

wherein the sample aerosol particles are received from the open atmosphere.

6. The method as in claim 1,

wherein the sample aerosol particles are from a test specimen.

7. The method as in claim 6,

wherein the sample aerosol particles are received from a sampling volume containing the test specimen.

8. The method as in claim 6,

further comprising generating the sample aerosol particles from the test specimen.

9. The method as in claim 8,

wherein the sample aerosol particles are generated by blowing air on the test specimen.

10. The method as in claim 8,

wherein the sample aerosol particles are generated by agitating the test specimen.

11. The method as in claim 1,

further comprising communicating to a user in real time the identity determination of the individual aerosol particle.

12. The method as in claim 11,

wherein the real time communication includes notifying the user when a specific known particle type is identified.

13. The method as in claim 11,

wherein the real time communication includes notifying the user when a specific chemical composition is identified.

14. The method as in claim 11,

wherein the real time communication includes displaying the identity determination to the user.

15. The method as in claim 14,

wherein the displayed identity determination indicates concentration level of the identified individual aerosol particle with respect to all analyzed sample aerosol particles.

16. The method as in claim 1,

wherein the bipolar single particle mass spectrometer is an aerosol time-of-flight mass spectrometer.

17. A method of detecting in real time chemical and/or biological threat agents from a test specimen comprising:

placing the test specimen in an enclosure defining a sampling volume;

collecting sample aerosol particles from the sampling volume;

receiving the sample aerosol particles into a bipolar single particle mass spectrometer;

producing positive and negative test spectra of an individual aerosol particle using the bipolar single particle mass spectrometer;

comparing each test spectrum to spectra of the same respective polarity in a database of predetermined positive and negative spectra for known particle types including threat agents, to produce a similarity score for each predetermined spectrum and obtain a set of substantially matching spectra based on a predetermined similarity score threshold;

determining the identity of the individual aerosol particle from the set of substantially matching spectra by determining a best matching one of the known particle types having both a substantially matching positive spectrum and a substantially matching negative spectrum associated therewith from the set, with at least one of the substantially matching positive and negative spectra having the highest order similarity score of all substantially matching spectra of the same respective polarity; and

notifying a user upon identifying the individual aerosol particle as a threat agent from the known particle types.

18. The method as in claim 17,

wherein the comparison of each test spectrum to the database includes converting each test spectrum into a corresponding test spectrum vector, and vector multiplying the test spectrum vector with a transpose of a predetermined spectrum vector of the same respective polarity to calculate the similarity score.

19. The method as in claim 17,

further comprising generating the sample aerosol particles from test specimen into the sampling volume.

20. The method as in claim 19,

wherein the sample aerosol particles are generated by blowing air on the test specimen.

21. The method as in claim 19,

wherein the sample aerosol particles are generated by agitating the test specimen.

22. The method as in claim 17,

wherein the user notification includes displaying the identity determination of the threat agent to the user.

23. The method as in claim 22,

wherein the displayed identity determination indicates concentration level of the identified threat agent with respect to all analyzed sample aerosol particles.

24. A system for identifying individual aerosol particles in real time comprising:

a bipolar single particle mass spectrometer adapted to receive sample aerosol particles and produce positive and negative test spectra of individual aerosol particles;

a data storage medium;

a database of predetermined positive and negative spectra for known particle types stored on the data storage medium; and

a data processor having a first data processing module adapted to compare each test spectra to spectra of the same respective polarity in the database to obtain a set of substantially matching spectra, and a second data processing module adapted to determine the identity of the individual aerosol particle from the set of substantially matching spectra by determining a best matching one of the known particle types having both a substantially matching positive spectrum and a substantially matching negative spectrum associated therewith from the set.

25. The system as in claim 24,

wherein the first data processing module produces a similarity score for each comparison of the respective test spectra to the database of predetermined positive and negative spectra, and determines the set of substantially matching spectra based on a predetermined similarity score threshold.

26. The system as in claim 25,

wherein the best matching one of the known particle types has associated therewith, for at least one of the substantially matching positive and negative spectra, the highest order similarity score of all substantially matching spectra of the same respective polarity.

27. The system as in claim 24,

wherein the first data processing module is adapted to convert each test spectrum into a corresponding test spectrum vector, and vector multiply the test spectrum vector with a transpose of a predetermined spectrum vector of the same respective polarity to calculate the similarity score.

28. The system as in claim 24,

further comprising means for collecting the sample aerosol particles from the open atmosphere.

29. The system as in claim 24,

further comprising means for collecting the sample aerosol particles from a test specimen.

30. The system as in claim 29,

further comprising an enclosure defining a sampling volume for receiving the test specimen, wherein the sample aerosol particles are collected from the sampling volume.

31. The system as in claim 29,

further comprising an aerosol generator for generating the sample aerosol particles from the test specimen.

32. The system as in claim 31,

wherein the aerosol generator is adapted to blow air on the test specimen.

33. The system as in claim 31,

wherein the aerosol generator is adapted to agitate the test specimen.

34. The system as in claim 24,

further comprising means for communicating to a user in real time the identity of the individual aerosol particle.

35. The system as in claim 34,

wherein the means for real time communication notifies the user when a specific known particle type is identified.

36. The system as in claim 34,

wherein the means for real time communication notifies the user when a specific chemical composition is identified.

37. The system as in claim 34,

wherein the means for real time communication displays the identity determination to the user.

38. The system as in claim 37,

wherein the displayed identity determination indicates concentration level of the identified individual aerosol particle with respect to all analyzed sample aerosol particles.

39. The system as in claim 24,

wherein the bipolar single particle mass spectrometer is an aerosol time-of-flight mass spectrometer.

40. A method of identifying individual aerosol particles in real time comprising:

receiving sample aerosol particles;

producing positive and negative test spectra of an individual aerosol particle using a bipolar single particle mass spectrometer;

comparing each test spectrum to spectra of the same respective polarity in a database of predetermined positive and negative spectra for known particle types so that a similarity score is produced for each predetermined spectrum anc a set of substantially matching spectra is obtained based on a predetermined similarity score threshold; and

determining the identity of the individual aerosol particle from the set of substantially matching spectra by determining a best matching one of the known particle types having both a substantially matching positive spectrum and a substantially matching negative spectrum associated therewith from the set, wherein the best matching one of the known particle types has associated therewith a substantially matching positive spectrum with the highest order similarity score of all substantially matching positive spectra.

41. A method of identifying individual aerosol particles in real time comprising:

receiving sample aerosol particles;

producing positive and negative test spectra of an individual aerosol particle using a bipolar single particle mass spectrometer;

comparing each test spectrum to spectra of the same respective polarity in a database of predetermined positive and negative spectra for known particle types so that a similarity score is produced for each predetermined spectrum and a set of substantially matching spectra is obtained based on a predetermined similarity score threshold; and

determining the identity of the individual aerosol particle from the set of substantially matching spectra by determining a best matching one of the known particle types having both a substantially matching positive spectrum and a substantially matching negative spectrum associated therewith from the set, wherein the best matching one of the known particle types has associated therewith a substantially matching negative spectrum with the highest order similarity score of all substantially matching negative spectra.

42. A method of detecting in real time chemical and/or biological threat agents from a test specimen comprising:

placing the test specimen in an enclosure defining a sampling volume;

collecting sample aerosol particles from the sampling volume;

receiving the sample aerosol particles into a bipolar single particle mass spectrometer;

producing positive and negative test spectra of an individual aerosol particle using the bipolar single particle mass spectrometer;

comparing each test spectrum to spectra of the same respective polarity in a database of predetermined positive and negative spectra for known particle types including threat agents, to produce a similarity score for each predetermined spectrum and obtain a set of substantially matching spectra based on a predetermined similarity score threshold;

determining the identity of the individual aerosol particle from the set of substantially matching spectra by determining a best matching one of the known particle types having both a substantially matching positive spectrum and a substantially matching negative spectrum associated therewith from the set, wherein the best matching one of the known particle types has associated therewith a substantially matching positive spectrum with the highest order similarity score of all substantially matching positive spectra; and

notifying a user upon identifying the individual aerosol particle as a threat agent from the known particle types.

43. A method of detecting in real time chemical and/or biological threat agents from a test specimen comprising:

placing the test specimen in an enclosure defining a sampling volume;

collecting sample aerosol particles from the sampling volume;

receiving the sample aerosol particles into a bipolar single particle mass spectrometer;

producing positive and negative test spectra of an individual aerosol particle using the bipolar single particle mass spectrometer;

comparing each test spectrum to spectra of the same respective polarity in a database of predetermined positive and negative spectra for known particle types including threat agents, to produce a similarity score for each predetermined spectrum and obtain a set of substantially matching spectra based on a predetermined similarity score threshold;

determining the identity of the individual aerosol particle from the set of substantially matching spectra by determining a best matching one of the known particle types having both a substantially matching positive spectrum and a substantially matching negative spectrum associated therewith from the set, wherein the best matching one of the known particle types has associated therewith a substantially matching negative spectrum with the highest order similarity score of all substantially matching negative spectra; and

notifying a user upon identifying the individual aerosol particle as a threat agent from the known particle types.

44. A system for identifying individual aerosol particles in real time comprising:

a bipolar single particle mass spectrometer adapted to receive sample aerosol particles and produce positive and negative test spectra of individual aerosol particles;

a data storage medium;

a database of predetermined positive and negative spectra for known particle types stored on the data storage medium; and

a data processor having;

a first data processing module adapted to compare each test spectra to spectra of the same respective polarity in the database so that a similarity score is produced for each comparison of the respective test spectra to the database of predetermined positive and negative spectra, and a set of substantially matching spectra is determinably obtained based on a predetermined similarity score threshold; and

a second data processing module adapted to determine the identity of the individual aerosol particle from the set of substantially matching spectra by determining a best matching one of the known particle types having both a substantially matching positive spectrum and a substantially matching negative spectrum associated therewith from the set, wherein the best matching one of the known particle types has associated therewith a substantially matching positive spectrum with the highest order similarity score of all substantially matching positive spectra.

45. A system for identifying individual aerosol particles in real time comprising:

a bipolar single particle mass spectrometer adapted to receive sample aerosol particles and produce positive and negative test spectra of individual aerosol particles;

a data storage medium;

a database of predetermined positive and negative spectra for known particle types stored on the data storage medium; and

a data processor having;

a first data processing module adapted to compare each test spectra to spectra of the same respective polarity in the database so that a similarity score is produced for each comparison of the respective test spectra to the database of predetermined positive and negative spectra, and a set of substantially matching spectra is determinably obtained based on a predetermined similarity score threshold; and

a second data processing module adapted to determine the identity of the individual aerosol particle from the set of substantially matching spectra by determining a best matching one of the known particle types having both a substantially matching positive spectrum and a substantially matching negative spectrum associated therewith from the set, wherein the best matching one of the known particle types has associated therewith a substantially matching negative spectrum with the highest order similarity score of all substantially matching negative spectra.