Multimode ionization source

• US 20040079881A1
• Filed: 08/13/2003
• Published: 04/29/2004
• Est. Priority Date: 09/18/2002
• Status: Active Grant

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Fischer, Steven M., Bertsch, James L., Gourley, Darrell L.
• Granted Patent: US 7,078,681 B2
• Time in Patent Office: Days
• US Class Current: 250/288
• 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 49/107 Arrangements for using several ion sources
• CPC Class Codes: H01J 49/162 Direct photo-ionisation, e.g. single photon or multi-photon ionisation
• CPC Class Codes: H01J 49/165 Electrospray ionisation
• CPC Class Codes: H01J 49/168 field ionisation, e.g. corona discharge atmospheric pressure corona discharge per se H01T19/00

Abstract

The present invention provides an apparatus and method for use with a mass spectrometer. The multimode ionization source of the present invention provides one or more atmospheric pressure ionization sources (e.g., electrospray, atmospheric pressure chemical ionization and/or atmospheric pressure photoionization) for ionizing molecules. A method of producing ions using the multimode ionization source is also disclosed. The apparatus and method provide the advantages of the combined ion sources without the inherent disadvantages of the individual sources. In an embodiment, the multimode ionization source includes an infrared emitter enclosed in an inner chamber for drying a charged aerosol. ESI/APCI multimode sources may include a corona needle shield and/or an auxiliary electrode.

Claims

1. A multimode ionization source, comprising:

(a) an electrospray ionization source for providing a charged aerosol;

(b) an infrared emitter adjacent to the electrospray ionization source for drying the charged aerosol;

(c) an atmospheric pressure ionization source downstream from the electrospray ionization source for further ionizing said charged aerosol; and

(d) a conduit adjacent to the atmospheric pressure ionization source and having an orifice for receiving ions from the charged aerosol.

2. The multimode ionization source of claim 1, wherein the atmospheric pressure ionization source is an atmospheric pressure photo-ionization (APPI) source.

3. The multimode ionization source of claim 1, wherein the atmospheric pressure ionization source is an atmospheric pressure chemical ionization (APCI) source.

4. The multimode ionization source of claim 1, further comprising:

a first electrode interposed between the electrospray ionization source and the conduit; and

a second electrode interposed between the first electrode and the orifice for guiding ions toward the orifice.

5. The multimode ionization source of claim 1, wherein the infrared emitter comprises an infrared (IR) lamp situated within an enclosure.

6. The multimode ionization source of claim 5, wherein the enclosure is configured to confine heat arising from the infrared lamp within the enclosure, and the enclosure includes an exit adjacent to the orifice of the conduit.

7. The multimode ionization source of claim 1, wherein the infrared emitter radiates at a wavelength between about 2 and 6 microns.

8. The multimode ionization source of claim 1, wherein the electrospray ionization source has a longitudinal axis and the conduit has a longitudinal axis and wherein the longitudinal axis of the electrospray ionization source is substantially orthogonal to the longitudinal axis of the conduit.

9. A mass spectrometer for multimode ion production, comprising:

(a) a multimode ionization source comprising;

i. an electrospray ionization source for providing a charged aerosol;

ii. an infrared emitter adjacent to the electrospray ionization source for drying the charged aerosol;

iii. an atmospheric pressure ionization source downstream from the electrospray ionization source for further ionizing said charged aerosol; and

iv. a conduit adjacent to the atmospheric pressure ionization source and having an orifice for receiving ions from the charged aerosol; and

(b) a detector downstream from the multimode ionization source for detecting the ions produced by the multimode ionization source.

10. The mass spectrometer for multimode ion production of claim 9, wherein the atmospheric pressure ionization source is an atmospheric pressure photo-ionization (APPI) source.

11. The mass spectrometer for multimode ion production of claim 9, wherein the atmospheric pressure ionization source is an atmospheric pressure chemical ionization (APCI) source.

12. The mass spectrometer for multimode ion production of claim 9, wherein the multimode ionization source further comprises:

a first electrode interposed between the electrospray ionization source and the conduit; and

a second electrode interposed between the first electrode and the orifice for guiding ions toward the orifice of the conduit.

13. The mass spectrometer for multimode ion production of claim 9, wherein the infrared emitter comprises an infrared (IR) lamp situated within an enclosure.

14. The mass spectrometer for multimode ion production of claim 9, wherein the electrospray ionization source has a longitudinal axis and the conduit has a longitudinal axis and wherein the longitudinal axis of the electrospray ionization source is substantially orthogonal to the longitudinal axis of the conduit.

15. A method of producing ions using a multimode ionization source, comprising:

(a) producing a charged aerosol by electrospray ionization;

(b) exposing the charged aerosol to infrared radiation, the infrared radiation drying the aerosol;

(c) further ionizing the charged aerosol using an atmospheric pressure ionization source; and

(d) detecting the ions produced from the multimode ionization source.

16. The method of claim 15, wherein the atmospheric pressure ionization source is an atmospheric pressure photo-ionization (APPI) source.

17. The method of claim 15, wherein the atmospheric pressure ionization source is an atmospheric pressure chemical ionization (APCI) source.

18. The method of claim 15, further comprising:

(e) guiding the charged aerosol downstream using electrodes.

19. The method of claim 15, further comprising:

(f) confining the charged aerosol within an enclosed area as it is exposed to the infrared radiation.

20. A multimode ionization source, comprising:

(a) a source housing;

(b) a nebulizer disposed in the source housing and having an orifice for providing a charged aerosol;

(c) a corona needle disposed in the housing and positioned downstream from the nebulizer for further ionizing the charged aerosol;

(d) a shield substantially enclosing the corona needle; and

(e) a conduit having an orifice adjacent to the corona needle for receiving ions from the charged aerosol.

21. The multimode ionization source of claim 20, further comprising:

(f) a drying device adjacent to the orifice of the nebulizer for drying the charged aerosol;

22. The multimode ionization source of claim 20, wherein the shield is configured to substantially isolate the corona needle from a flow of the charged aerosol.

23. The multimode ionization source of claim 22, wherein the shield substantially surrounds the corona needle and has an exit allowing passage of a discharge from the corona needle.

24. The multimode ionization source of claim 21, wherein the drying device comprises an infrared emitter.

25. The multimode ionization source of claim 20, wherein a voltage is applied to the shield.

26. The multimode ionization source of claim 20, further comprising:

(g) a first electrode interposed between the orifice of the nebulizer and the orifice of the conduit for producing ions from the orifice of the nebulizer; and

(h) a second electrode interposed between the first electrode and the orifice of the conduit and positioned upstream from the corona needle for directing ions from the first electrode toward the orifice of the conduit.

27. A method of producing ions using a multimode source including an ESI source and an APCI source, comprising:

(a) producing a charged aerosol using the ESI source;

(b) producing a discharge with a corona needle having a shield; and

(c) exposing the charged aerosol to the discharge.

28. The method of claim 27, further comprising:

(d) drying the charged aerosol produced by the ESI source.

29. The method of claim 28, wherein the drying comprises exposing the charged aerosol to an emission of infrared radiation.

30. The method of claim 27, wherein the shield substantially surrounds the corona needle and has an exit for allowing passage of the discharge.

31. The method of claim 27, further comprising:

(d) guiding the charged aerosol after exposure to the discharge toward an entrance of a mass analyzer by subjecting the charged aerosol to an electric field.

32. The method of claim 31, wherein the electric field is generated by applying a voltage to the shield.

33. A multimode ionization source, comprising:

(a) a source housing;

(b) a nebulizer disposed in the source housing and having an orifice for providing a charged aerosol;

(c) a corona needle disposed in the housing and positioned downstream from the nebulizer for further ionizing the charged aerosol;

(d) an auxiliary electrode adjacent to the corona needle; and

(e) a conduit having an orifice adjacent to the corona needle for receiving ions from the charged aerosol.

34. The multimode ionization source of claim 33, further comprising:

(f) a drying device adjacent to the orifice of the nebulizer for drying the charged aerosol.

35. The multimode ionization source of claim 34, wherein the drying device comprises an infrared emitter.

36. The multimode ionization source of claim 33, wherein the auxiliary electrode is positioned between the corona needle and the orifice of the conduit and has a portion extending toward the corona needle, the auxiliary electrode generating an electric field that guides ions in the charged aerosol toward the orifice.

37. The multimode ionization source of claim 33, further comprising:

(g) a second electrode interposed between the orifice of the nebulizer and the orifice of the conduit for producing ions from the orifice of the nebulizer; and

(h) a third electrode interposed between the first electrode and the orifice of nebulizer and positioned upstream from the corona needle for directing ions from the first electrode toward the orifice of the conduit.

38. A method of producing ions using a multimode source including an ESI source and an APCI source having a corona needle, the comprising:

(a) producing a charged aerosol using the ESI source;

(b) exposing the charged aerosol to a discharge from the corona needle, further ionizing the charged aerosol; and

(c) guiding ions in the charged aerosol using a auxiliary electrode after the charged aerosol is exposed to the discharge.

39. The method of claim 38, further comprising:

(d) drying the charged aerosol produced by the ESI source.

40. The method of claim 39, wherein the drying comprises exposing the charged aerosol to an emission of infrared radiation.

41. The method of claim 38, wherein the auxiliary electrode has a portion extending toward the corona needle.

42. The method of claim 38, wherein the auxiliary electrode guides ions in the charged aerosol toward an entrance of a mass analyzer.