Ion source with controlled superpositon of electrostatic and gas flow fields

• US 20050194542A1
• Filed: 02/22/2005
• Published: 09/08/2005
• Est. Priority Date: 02/23/2004
• Status: Active Grant

• Current Assignee: Andreas Hieke
• Original Assignee: Ciphergen Biosystems Incorporated
• Inventors: Hieke, Andreas
• Granted Patent: US 7,138,642 B2
• Time in Patent Office: Days
• US Class Current: 250/400
• CPC Class Codes: H01J 49/0481 with means for collisional cooling
• CPC Class Codes: H01J 49/062 Ion guides linear ion traps performing mass selection H01J49/4225, mass filters H01J49/421
• CPC Class Codes: H01J 49/164 Laser desorption/ionisation, e.g. matrix-assisted laser desorption/ionisation [MALDI] sample holders H01J49/0418

Abstract

Ion source devices with controlled superposition of electrostatic and gas flow fields to effect rapid collisional cooling with improved ion collection and collimation, analytical apparatus comprising such ion source devices, and methods for use are presented.

Claims

1. A device for outputting ions, the device comprising:

a first housing; and

a second housing,

wherein said first housing comprises at least one pneumatic element that segregates the space within the first housing into a gas reservoir and an ion expansion chamber, the gas reservoir being in axisymmetric gas communication with the ion expansion chamber and in gas communication with the exterior of said first housing;

wherein said second housing comprises at least one pneumatic element that segregates the space within the second housing into an axial trajectory region and a gas sink region, the gas sink region being in axisymmetric gas communication with the axial trajectory region and in gas communication with the exterior of said second housing;

wherein the first housing expansion chamber is axially aligned with and in gas and ion communication with the second housing axial trajectory region and wherein the second housing axial trajectory region is in axial alignment with and in ion communication with an ion outlet of the device,

wherein ions introduced into the ion expansion chamber are guided during use along the device axis from the expansion chamber through the axial trajectory region to the ion outlet by pneumatic and electrostatic fields, and

wherein the pneumatic and electrostatic fields are superposed.

2. The device of claim 1, wherein the ions guided during use are guided predominantly by pneumatic fields in the first housing and predominantly by electrostatic fields in the second housing.

3. The device of claim 1, wherein said first housing comprises a plurality of pneumatic elements that segregate the space within the first housing into a gas reservoir and an ion expansion chamber, the gas reservoir being in axisymmetric gas communication with the ion expansion chamber and in gas communication with the exterior of said first housing.

4. The device of claim 3, wherein said second housing comprises a plurality of pneumatic elements that segregate the space within the second housing into an axial trajectory region and a gas sink region, the gas sink region being in axisymmetric gas communication with the axial trajectory region and in gas communication with the exterior of said second housing.

5. The device of claim 3, wherein at least a portion of the plurality of said first housing pneumatic elements is electrically conductive.

6. The device of claim 5, wherein each of the plurality of first housing pneumatic elements is electrically conductive.

7. The device of claim 5 or 6, wherein said first housing electrically conductive elements are capable of creating an electric field that is capable of affecting ion trajectory in the ion expansion chamber.

8. The device of claim 4, wherein at least a portion of the plurality of said second housing pneumatic elements is electrically conductive.

9. The device of claim 8, wherein each of the plurality of second housing pneumatic elements is electrically conductive.

10. The device of claim 8 or 9, wherein said second housing electrically conductive elements are capable of creating an electrostatic field capable of guiding ions axially through the axial trajectory region to a device outlet that communicates the axial trajectory region with the exterior of said second housing.

11. The device of claim 1, further comprising:

means for introducing ions into the expansion chamber.

12. The device of claim 11, wherein said means comprises engagement means for a laser desorption ionization probe, the engagement means being capable of positioning a laser desorption ionization probe so as to display at least one surface thereof to the expansion chamber.

13. The device of claim 12, wherein said probe engagement means is in physical and electrical contiguity to an electrically conductive element.

14. The device of claim 1, wherein said first housing comprises at least one gas inlet that communicates the gas reservoir with the exterior of said first housing.

15. The device of claim 14, wherein said second housing comprises at least one gas outlet that communicates the gas sink region with the exterior of said second housing.

16. The device of claim 1, wherein one or more of said at least one first housing pneumatic elements is so shaped and so disposed that maximal constriction to axisymmetric gas flow between the gas reservoir and expansion chamber is located proximal to the expansion chamber.

17. The device of claim 1, wherein the gas communication between the gas reservoir and expansion chamber is continuously axisymmetric.

18. The device of claim 1, wherein the gas communication between the gas reservoir and expansion chamber is periodically axisymmetric.

19. The device of claim 1, wherein said first and second housings are of integral construction.

31. Analytical apparatus, comprising:

an ion source device according to claim 1, operably coupled to

an ion analytical instrument.

32. The analytical apparatus of claim.31, wherein said ion analytical instrument comprises at least one RF multipole ion guide.

33. The analytical apparatus of claim 32, wherein at least one of the at least one multipoles is a quadrupole, a hexapole, or an octapole.

34. The analytical apparatus of claim 32, wherein the operative coupling of said ion source to said ion analytical instrument permits said ion source to draw gas proximally outward from said multipole during use.

35. The analytical apparatus of claim 31, wherein the ion analytical instrument comprises at least one mass analyzer.

36. The analytical apparatus of claim 31, wherein the ion analytical instrument comprises a plurality of mass analyzers.

40. The method of claim 37, wherein said ion source device is a device according to claim 1 or claim 31.

41. The method of claim 40, wherein the magnitude of the gas flows is controlled in part by controlling gas flows into the gas reservoir.

20. An ion source device, the device comprising:

ion introduction or generating means;

first ion guidance means; and

second ion guidance means,

wherein said first ion guidance means are configured to establish a first superposed electrostatic fields and pneumatic fields,

wherein said second ion guidance means are configured to establish a second superposed electrostatic fields and pneumatic fields,

and wherein, during use, ions introduced or generated by said ion introducing or generating means are guided by the first and second superposed electrostatic fields and pneumatic fields along the device axis to a device outlet.

21. The device of claim 20, wherein the pneumatic fields of the first superposed fields is predominantly ion-guiding in the first housing, and wherein the electrostatic fields of the second superposed fields is predominantly ion-guiding in the second housing.

22. The device of claim 20, wherein said first ion guidance means is disposed in a first housing, wherein said second ion guidance means is disposed in a second housing, and wherein said first housing is in axial ion and gas flow communication with said second housing.

23. The device of claim 22, wherein said first ion guidance means comprises at least one electropneumatic element, the at least one electropneumatic element segregating the space within the first housing into a gas reservoir and an ion expansion chamber, the gas reservoir being in axisymmetric gas communication with the ion expansion chamber.

24. The device of claim 22, wherein at least one of said electropneumatic elements is so shaped and so disposed within said first housing as to create radially inwardly-directed axisymmetric gas flow when the gas reservoir is at a higher pressure than the expansion chamber.

25. The device of claim 22, wherein said second ion guidance means comprises at least one electropneumatic element, the at least one electropneumatic element segregating the space within the second housing into an axial trajectory region and a gas sink region, the axial trajectory region being in axisymmetric gas communication with the gas sink region.

26. The device of claim 25, wherein at least one of said electropneumatic elements is so shaped and so disposed within said second housing as to create radially outward-directed axisymmetric gas flow when the axial trajectory region is at a higher pressure than the gas sink region.

27. The device of claim 22, wherein said first housing comprises at least one symmetrically disposed gas inlet that communicates the gas reservoir with the exterior of the first housing.

28. The device of claim 22, wherein said second housing comprises at least one gas outlet that communicates the gas sink region with the exterior of the second housing.

29. The device of claim 20, wherein said ion generating means generates ions within the expansion chamber.

30. The device of claim 29, wherein said ion generating means is a laser desorption ionization ion source.

37. A method of increasing the collimated output of ions from an ion source device, the method comprising:

guiding ions introduced into or generated within said source along the device axis to an ion source outlet using superposed electrostatic and axisymmetric pneumatic fields.

38. The method of claim 37, wherein ion-guiding pneumatic fields predominate in their effects on ion motion over electrostatic fields in a first portion of the ion trajectory and ion-guiding electrostatic fields predominate in their effects on ion motion over pneumatic fields in a second portion of the ion trajectory

39. The method of claim 37, wherein the pneumatic fields are generated by establishing radially-inward axisymmetric and radially-outward axisymmetric gas flows in axial succession.

42. The method of claim 37, wherein the electrostatic fields are generated by applying an electrical potential to each of a plurality of electrically conductive elements in said ion source device.

43. The method of claim 37, further comprising a subsequent step of:

performing at least one analysis on at least one species of ion output from said ion source device.

44. The method of claim 43, wherein said at least one analysis comprises:

determining the at least one ion'"'"'s mass to charge ratio.

45. The method of claim 37, further comprising the subsequent steps of:

selecting at least one ion species output from said ion source device;

fragmenting said at least one selected ion species; and

performing at least one analysis on at least one product ion resulting from fragmenting said at least one selected ion.

46. The method of claim 45, wherein performing said at least one analysis comprises:

determining the mass to charge ratio of said at least one product ion.

47. The method of claim 37, further comprising, before the step of guiding ions, the step of:

introducing ions into or generating ions within said ion source device.

48. The method of claim 47, wherein introducing or generating ions comprises:

generating ions by laser desorption ionization of an analytical sample.

49. The method of claim 48, wherein said analytical sample comprises proteins and said ions are ions generated from said proteins.

50. The method of claim 49, further comprising the step, before generating ions, of:

capturing proteins from an inhomogeneous mixture on a surface of a laser desorption ionization probe.