Ion beam mass pre-separator

Patent metadata

Field	Value
Publication number	US-10199208-B2
Application number	US-201615060474-A
Country	US
Kind code	B2
Filing date	Mar 3, 2016
Priority date	Mar 3, 2016
Publication date	Feb 5, 2019
Grant date	Feb 5, 2019

Abstract

An apparatus for separating ions includes an electrode arrangement having a length extending between first and second ends. The first end is configured to introduce a beam of ions into an ion transmission space of the arrangement. An electronic controller applies an RF potential and a DC potential to an electrode of the electrode arrangement, for generating a ponderomotive RF electric field and a mass-independent DC electric field. The application of the potentials is controlled such that a ratio of the strength of the ponderomotive RF electric field to the strength of the mass-independent DC electric field varies along the length of the electrode arrangement. The generated electric field supports extraction of ions having different m/z values at respective different positions along the length of the electrode arrangement. Ions are extracted in one of increasing and decreasing sequential order of m/z ratio with increasing distance from the first end.

First claim

What is claimed is:

1. An apparatus for separating ions spatially and in sequential order of mass-to-charge (m/z) ratio, the apparatus comprising:
an electrode arrangement having a length extending in an axial direction between a first end thereof and a second end thereof, the second end opposite the first end, and the first end being configured to introduce a beam of ions into an ion transmission space of the electrode arrangement, the beam of ions comprising ions having m/z ratios within a first range of m/z ratios; and
an electronic controller in electrical communication with the electrode arrangement and configured to apply an RF potential and a DC potential to at least an electrode of the electrode arrangement for generating a ponderomotive RF electric field and a mass-independent DC electric field, such that a ratio of the strength of the ponderomotive RF electric field to the strength of the mass-independent DC electric field in a transverse dimension orthogonal to the axial direction varies along the length of the electrode arrangement,

wherein the generated electric field supports the extraction of ions having different m/z values at respective different positions along the length of the electrode arrangement, in one of increasing and decreasing sequential order of m/z ratio with increasing distance from the first end;
wherein the electrode arrangement comprises a single quadrupole electrode assembly comprising a substantially parallel arrangement of four non-segmented, rod-shaped electrodes; and,
wherein the electronic controller is configured to apply the RF potential to at least some of the non-segmented rod-shaped electrodes.

2. The apparatus of claim 1 comprising at least one DC-biased extraction electrode disposed adjacent to a first side of the quadrupole electrode assembly for controlling the DC electric field within the ion transmission space of the electrode arrangement, the at least one DC-biased extraction electrode defining a plurality of discrete extraction regions of the quadrupole electrode assembly, wherein each discrete extraction region supports the extraction of a subset of the beam of ions, each subset forming a beamlet of ions having m/z ratios within a different predetermined range of m/z ratios.

3. The apparatus of claim 2 wherein the at least one DC-biased extraction electrode comprises a plurality of DC-biased extraction electrodes.

4. The apparatus of claim 3 wherein the spacing between the quadrupole electrode assembly and each DC-biased extraction electrode of the plurality of DC-biased extraction electrodes is substantially the same, and wherein the electronic controller is configured to apply the DC potential to the plurality of DC-biased extraction electrodes as a series of different DC potentials that increases monotonically from one DC-biased extraction electrode to the next in a direction along the length of the electrode arrangement from the first end to the second end.

5. The apparatus of claim 3 wherein the spacing between the quadrupole electrode assembly and each DC-biased extraction electrode of the plurality of DC-biased extraction electrodes decreases monotonically from one DC-biased extraction electrode to the next in a direction along the length of the electrode arrangement from the first end to the second end, and wherein the electronic controller is configured to apply the same DC potential to all of the DC-biased extraction electrodes of the plurality of DC-biased extraction electrodes.

6. The apparatus of claim 2 wherein the at least one DC-biased extraction electrode comprises a shaped-electrode with one edge having a plurality of protruding portions, wherein the spacing between the quadrupole electrode assembly and each protruding portion decreases monotonically along the length of the electrode arrangement from the first end to the second end, and wherein the electronic controller is configured to apply the DC potential to the shaped-electrode.

7. The apparatus of claim 2 wherein the at least one DC-biased extraction electrode is fabricated from a resistive material and the electronic controller is configured to apply the DC potential to the at least one DC-biased extraction electrode such that the DC potential increases in a direction from the first end toward the second end.

8. The apparatus of claim 1 wherein at least one of the non-segmented, rod-shaped electrodes is fabricated from a resistive material and the electronic controller is configured to apply the DC potential to the at least one of the non-segmented, rod-shaped electrodes such that the DC potential increases in a direction from the first end toward the second end.

9. The apparatus of claim 2 comprising a plurality of DC-biased compensating electrodes disposed adjacent to a second side of the quadrupole electrode assembly that is opposite the first side, at least one DC-biased compensating electrode of the plurality of DC-biased compensating electrodes being aligned with each discrete extraction region.

10. The apparatus of claim 2 , wherein the at least one DC-biased extraction electrode comprises at least one pair of DC-biased extraction electrodes, which are spaced apart one from the other to define a gap therebetween through which gap the ions are extracted from the ion transmission space.

11. The apparatus of claim 1 wherein the electrode arrangement comprises a quadrupole electrode assembly comprising a substantially parallel arrangement of four segmented, rod-shaped electrodes, the electronic controller being configured to apply the RF potential to segments of at least some of the segmented rod-shaped electrodes.

12. The apparatus of claim 11 wherein the segments of one of the four segmented, rod-shaped electrodes have an aperture extending therethrough for supporting extraction of the ions, and wherein the electronic controller is configured to apply the DC potential to the segments of the one of the rod-shaped electrodes as a series of DC potentials that increase monotonically from one segment to next in a direction from the first end toward the second end.

13. The apparatus of claim 1 wherein the electrode arrangement comprises an ion tunnel comprising a plurality of ring-shaped electrodes disposed in a stacked-arrangement with the ion transmission space extending in the stacking direction.

14. A mass spectrometer system, comprising:
a continuous flux ion source for producing a beam of ions comprising ions having a first range of mass-to-charge (m/z) ratios;
an ion flux separator disposed in fluid communication with the ion source and comprising:

an electrode arrangement having a length extending in an axial direction between a first end thereof and a second end thereof, the second end opposite the first end, and the first end configured to introduce the beam of ions from the continuous flux ion source into an ion transmission space of the electrode arrangement;
wherein the electrode arrangement comprises a single quadrupole electrode assembly comprising a substantially parallel arrangement of four non-segmented, rod-shaped electrodes; and, wherein the electronic controller is configured to apply the RF potential to at least some of the non-segmented rod-shaped electrodes; and,
an electronic controller in electrical communication with the electrode arrangement and configured to apply an RF potential and a DC potential to at least an electrode of the electrode arrangement for generating a ponderomotive RF electric field and a mass-independent DC electric field, such that a ratio of the strength of the ponderomotive RF electric field to the strength of the mass-independent

Assignees

• Thermo Fisher Scient Bremen Gmbh
• Thermo Finnigan Llc

Inventors

• Grinfeld Dmitry E
• Ugarov Mikhail V
• Kovtoun Viatcheslav V
• Makarov Alexander A

Classifications

• H01J49/063 Primary

  Multipole ion guides, e.g. quadrupoles, hexapoles · CPC title

• H01J49/423 Primary

  with radial ejection · CPC title

• H01J49/0031

  Step by step routines describing the use of the apparatus (H01J49/0081 takes precedence) · CPC title

• H01J49/4255

  with particular constructional features · CPC title

• H01J49/427 Primary

  Ejection and selection methods · CPC title