Sampling system for use with surface ionization spectroscopy

Abstract

In various embodiments of the invention, a device permits more efficient collection and transmission of ions produced by the action of a carrier gas containing metastable neutral excited-state species into a mass spectrometer. In one embodiment of the invention, the device incorporates the source for ionization in combination with a jet separator to efficiently remove excess carrier gas while permitting ions to be more efficiently transferred into the vacuum chamber of the mass spectrometer. In an embodiment of the invention, improved collection of ions produced by the carrier gas containing metastable neutral excited-state species at greater distances from between the position of the analyte and the position of the mass spectrometer are enabled.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention will be described in detail based on the following figures, wherein:

FIG. 1 is a diagram of a prior art jet separator as used with a conventional GC/MS instrument;

FIG. 2 is a schematic diagram of a prior art jet separator with a conventional GC/MS high vacuum ionization source;

FIG. 3 is a schematic diagram of a typical API-MS of the prior art;

FIG. 4(A) is a schematic diagram of a jet separator as a means of transferring ions into a MS with skimmers-based API inlet in accordance with one embodiment of the present invention;

FIG. 4(B) is a schematic diagram of a jet separator as a means of transferring ions into a MS with a capillary-type API inlet in accordance with one embodiment of the present invention;

FIG. 4(C) is a schematic diagram of a jet separator as integrated with a conventional API-MS in accordance with one embodiment of the present invention;

FIG. 5 is a schematic diagram showing a jet separator fabricated with inlet and exit tubes in accordance with one embodiment of the present invention;

FIG. 6 is a schematic diagram showing an embodiment of the present invention where a jet separator is connected with a sampling tube;

FIG. 7 is a schematic diagram showing a jet separator with the grid at its inlet in accordance with one embodiment of the present invention;

FIG. 8 is a schematic diagram showing a jet separator with a grid at the inlet of the sampling tub in accordance with one embodiment of the present invention;

FIG. 9 is a schematic diagram of a jet separator fabricated with a grid between the inlet and exit tubes in accordance with one embodiment of the present invention;

FIG. 10 is a schematic diagram of a jet separator with a sampling tube and a grid and the sample connected to the sampling tube at a point intermediate the grid and the jet separator in accordance with one embodiment of the present invention;

FIG. 11 is a schematic diagram showing an effusion type separator in accordance with one embodiment of the present invention;

FIG. 12 is a schematic diagram showing an effusion type separator incorporating a wire mesh cage to which a potential can be applied in accordance with one embodiment of the present invention;

FIG. 13 is a schematic diagram showing an effusion type separator incorporating a perforated cage to which a potential can be applied in accordance with one embodiment of the present invention;

FIG. 14 is a schematic diagram showing a jet separator fabricated with inlet and outlet tubes having thicker diameter tubes compared with FIG. 4(c) in accordance with one embodiment of the present invention;

FIG. 15 is a schematic diagram showing a jet separator fabricated with inlet and outlet tubes having different inner diameter tubes in accordance with one embodiment of the present invention;

FIG. 16 is a schematic diagram showing a jet separator fabricated with inlet and outlet tubes having different lengths in accordance with one embodiment of the present invention;

FIG. 17 is a schematic diagram of a jet separator where the outlet tube of the gas separator spans more than one skimmer in accordance with one embodiment of the present invention;

FIG. 18 (i)-(vi) is the mass chromatogram trace of the relative abundance of ions sampled from the ionization region as a function of the potential applied to the surface of the inlet and outlet tube of the gas separator;

FIG. 19 (i)-(vi) is a total ion chromatogram trace of the relative abundance of ions sampled from the ionization region as a function of the relative vacuum being applied between the inlet and outlet tubes of the gas separator; and

FIG. 20 shows the mass spectra derived from the ionization of ambient atmosphere (i) after and (ii) prior to application of a vacuum to the gas separator.

Claims

1. A gas separator comprising: (a) an external ion source; and(b) a jet separator.

2. The gas separator of claim 1, further comprising a capacitive surface on the jet separator.

3. A mass spectrometer comprising the gas separator of claim 1.

4. A gas separator comprising: (a) an external ion source;(b) a plurality of substantially co-axial tubes, wherein the plurality of tubes are spaced such that there is a gap between the plurality of tubes; and(c) a vacuum region, wherein at least a portion of the plurality of co-axial tubes are located in the vacuum region.

5. The gas separator of claim 4, further comprising one or more wire mesh cage screens encircling one or more of the plurality of gaps between the plurality of substantially co-axial tubes.

6. The gas separator of claim 1, wherein the gas separator is made up of an inlet tube having a proximal end and a distal end and an outlet tube having a proximal end and a distal end; wherein the proximal end of the inlet tube is closest to and the distal end is furthest from the external ionization source; wherein the proximal end of the inlet tube is at a distance from the external ionization source of between: a lower limit of approximately 10−3 m; andan upper limit of approximately 101 m.

7. The gas separator of claim 6, further comprising a heater directed at least one of the proximal end of the inlet tube, the distal end of the inlet tube, the proximal end of the outlet tube and the distal end of the outlet tube.

8. The gas separator of claim 4, further comprising one or more capacitive surface on the one or more substantially co-axial tubes, wherein one or more potential are applied to the one or more capacitive surfaces.

9. The gas separator of claim 8, wherein one or more of the plurality of substantially co-axial tubes is made of a material selected from the group consisting of glass, resistively coated glass, glass lined metal tube, coated fused silica, metal coated fused silica, machinable glass, metal coated machinable glass, ceramic, metal coated ceramic and metal.

10. The gas separator of claim 8, wherein the plurality of substantially co-axial tubes is positioned between a region of approximately atmospheric pressure and a region of approximately high vacuum.

11. A method of detecting an analyte comprising: (a) providing a device including a mass spectrometer and a gas separator of claim 1;(b) generating an analyte ion; and(c) transporting the analyte ion into the mass spectrometer.

12. A system for detecting an analyte comprising: (a) an ionization source;(b) an inlet side tube having two ends, with one of the ends proximal to the ionization source;(c) a vacuum region;(d) an outlet side tube having two ends, with one of the ends distal to the ionization source; and(e) a detector of the analyte.

13. The system of claim 12, wherein the said detector is selected from the group consisting of mass spectrometer, raman spectrometer, electromagnetic absorption spectrometer, electromagnetic emission spectrometer and surface detection spectrometer.