Multimode ion source with improved ionization
A multimode ionization source with improved ionization characteristics that comprises an electrospray ionization source for providing a charged aerosol, an atmospheric pressure chemical ionization (APCI) source including a corona needle having an end positioned downstream from the electrospray ionization source for producing a discharge that further ionizes the charged aerosol, an assist gas inlet positioned adjacent to the corona needle for providing assist gas, the assist gas facilitating ionization of the charged aerosol by the corona discharge, and a conduit having an orifice for receiving ions from the charged aerosol.
1. A multimode ionization source comprising:
a) an electrospray ionization source for providing a charged aerosol;
b) an atmospheric pressure chemical ionization (APCI) source including a corona needle having an end positioned downstream from the electrospray ionization source for producing a discharge that further ionizes the charged aerosol;
c) an assist gas inlet positioned adjacent to the corona needle for providing assist gas, the assist gas facilitating ionization of the charged aerosol by the discharge; and
d) a conduit having an orifice for receiving ions from the charged aerosol.
2. The multimode ionization source, further comprising:
e) a drying device adjacent to the electrospray ionization source for drying the charged aerosol.
3. The multimode ionization source of claim 1 , wherein the assist gas comprises a noble gas.
4. The multimode ionization source of claim 1 , wherein the assist gas inlet provides assist gas symmetrically and concentrically around the end of the corona needle.
5. The multimode ionization source of claim 1 , wherein the corona needle comprises multiple corona discharge needles.
6. The multimode ionization source of claim 1 , wherein the assist gas inlet provides assist gas non-concentrically with respect to the end of the corona needle.
7. The multimode ionization source of claim 6 , wherein the assist gas inlet is positioned on a downstream side of the corona needle.
8. The multimode ionization source of claim 1 , further comprising:
an electrode positioned adjacent to the end of the corona needle for directing ions toward the conduit.
9. The multimode ionization source of claim 1 , further comprising:
a heating element concentrically surrounding the corona needle for preheating gas around the corona needle.
10. The multimode ionization source of claim 1 , further comprising:
a heating element positioned between the corona needle and the conduit.
11. A mass spectrometer comprising:
i) a multimode ionization source comprising:
a) an electrospray ionization source for providing a charged aerosol;
b) an atmospheric pressure chemical ionization (APCI) source including a corona needle having an end positioned downstream from the electrospray ionization source for producing a discharge that further ionizes the charged aerosol;
c) an assist gas inlet positioned adjacent to the corona needle for providing assist gas, the assist gas facilitating ionization of the charged aerosol by the discharge; and
d) a conduit having an orifice for receiving ions from the charged aerosol;
ii) a mass analyzer positioned at a downstream end of the conduit and receiving ions therefrom; and
iii) a detector downstream from the mass analyzer for detecting ions received from the mass analyzer.
12. The mass spectrometer of claim 11 , wherein the assist gas comprises a noble gas.
13. The mass spectrometer of claim 11 , wherein the multimode ionization source further comprises a drying device adjacent to the electrospray ionization source for drying the charged aerosol.
14. The mass spectrometer of claim 11 , wherein the assist gas inlet provides assist gas symmetrically and concentrically around the end of the corona needle.
15. The mass spectrometer of claim 11 , wherein the corona needle comprises multiple corona discharge needles.
16. The mass spectrometer of claim 11 , wherein the assist gas inlet provides assist gas non-concentrically with respect to the end of the corona needle.
17. A method of producing ions using a multimode ionization source comprising:
a) producing a charged aerosol by electrospray ionization;
b) guiding the charged aerosol downstream using electrodes;
c) providing an assist gas in the vicinity of a corona needle downstream from the electrodes; and
d) ionizing the charged aerosol using with a discharge from the corona needle facilitated by the assist gas.
18. The method of claim 17 , further comprising:
e) drying the aerosol produced by the electrospray ionization.
19. The method of claim 17 , wherein the assist gas comprises a noble gas.
20. The method of claim 17 , further comprising:
heating the assist gas.
21. The method of claim 17 , wherein the assist gas is provided around the corona needle symmetrically and concentrically.
22. The method of claim 17 , wherein the corona needle comprises multiple corona needles.
23. An ion source for a mass spectrometer comprising:
a corona needle positioned to create a discharge in proximity to a stream of analytes; and
an assist gas inlet positioned adjacent to the corona needle for providing assist gas, the assist gas facilitating ionization of the analytes by the corona needle discharge.