Ion guide for mass spectrometer

• US 20050247872A1
• Filed: 05/05/2005
• Published: 11/10/2005
• Est. Priority Date: 05/05/2004
• Status: Active Grant

• Current Assignee: MDS Incorporated (Molecular Devices), Applied Biosystems Canada Limited (Thermo Fisher Scientific Incorporated)
• Original Assignee: MDS Incorporated (Molecular Devices)
• Inventors: Chernushhevich, Igor, Loboda, Alexandre V.
• Granted Patent: US 7,456,388 B2
• Time in Patent Office: Days
• US Class Current: 250/288
• CPC Class Codes: H01J 49/062 Ion guides linear ion traps performing mass selection H01J49/4225, mass filters H01J49/421
• CPC Class Codes: H01J 49/401 characterised by orthogonal acceleration, e.g. focusing or selecting the ions, pusher electrode

Abstract

An ion guide 24 for a mass spectrometer 30 including means for ejecting ions of different mass-to-charge ratios from the ion guide towards a detector or other object or device. The ejecting means causes the ions to be ejected in a desired sequence. The ions travel at different rates according to their mass-to-charge ratios, so that they arrive at a desired point in space in a desired sequence, for example in a detector 56 of a mass spectrometer at substantially the same time.

Claims

1. A mass spectrometer comprising an ion guide and a mass analyzer,

the ion guide defining a guide axis and adapted to provide an ion control field comprising a component for restraining movement of ions normal to the guide axis and comprising a component for controlling movement of ions parallel the guide axis;

the field adapted to provide for sequential release of ions having varying mass-to-charge ratios from the guide according to the mass-to-charge ratios of the ions and along a path parallel to the guide axis;

the sequence adapted to provide for the arrival of ions of substantially all released mass-charge ratios within an extraction region of the mass analyzer disposed substantially along the guide axis at substantially the same time;

the mass analyzer adapted for simultaneous analysis of ions of varying mass-to-charge ratios.

2. The mass spectrometer of claim 1, wherein the ion guide field is adapted to provide for the release of ions of relatively high mass-to-charge ratios prior to the release of ions of relatively low mass-to-charge ratios.

3. The mass spectrometer of claim 1, wherein the mass analyzer comprises an orthogonal time-of-flight mass analyzer.

4. The mass spectrometer of claim 1, wherein the ion guide comprises a plurality of electrodes, and the ion control field comprises an electromagnetic field produced by applying one or more volatages to the electrodes.

5. The mass spectrometer of claim 4, wherein the one or more voltages comprise at least one alternating current voltage and at least one direct current voltage.

6. The mass spectrometer of claim 5, wherein the at least one alternating current voltage comprises a radio-frequency alternating current voltage.

7. The mass spectrometer of claim 1, wherein the ion guide is adapted to provide at least one relatively low-pressure region and at least one relatively high-pressure region in a gas, and the ion control field comprises pressure gradients.

8. A method of guiding ions differing in mass-to-charge ratios, comprising:

providing in an ion guide defining a guide axis an ion control field comprising a component for restraining movement of ions normal to the guide axis;

providing in the ion control field an accumulation potential profile for accumulating ions within a constrained space within the ion guide;

providing in the ion control field an ejection potential profile for sequentially ejecting ions of varying mass-to-charge ratios from the guide according to the mass-to-charge ratios of the ions and along a path parallel to the guide axis, such that all of the ejected ions arrive at an extraction region disposed substantially along the guide axis at substantially the same time.

9. The method of claim 8 comprising providing in the ion control field a pre-ejection profile for preventing ions from accumulating in the ion guide.

10. The method of claim 8, wherein the extraction region is an extraction region of a mass analyzer and the method comprises simultaneously analysing ions of varying mass-to-charge ratios.

11. An ion guide for a mass spectrometer, the ion guide defining a guide axis and adapted to generate at least one ion control field for restraining movement of ions normal to the guide axis and for controlling movement of ions parallel the guide axis;

the field adapted to provide for selective release of ions having varying mass-to-charge ratios from the guide according to a desired sequence of mass-to-charge ratios along a path parallel to the guide axis;

the sequence selectable to provide for the arrival of ions of substantially all released mass-to-charge ratios at a selected extraction region disposed substantially along the guide axis at substantially the same time.

12. The ion guide of claim 11, wherein the ion guide field is adapted to provide for the release of ions of relatively high mass-to-charge ratios prior to the release of ions of relatively low mass-to-charge ratios.

13. The ion guide of claim 11 comprising a plurality of electrodes, wherein the ion control field comprises an electromagnetic field produced by applying electrical voltages to the electrodes.

14. The ion guide of claim 13, wherein the voltages comprise alternating current and direct current voltages.

15. The ion guide of claim 14, wherein the alternating current voltage comprises radio-frequency alternating current voltage.

16. The ion guide of claim 11, wherein the ion guide is adapted to provide at least one relatively low-pressure region and at least one relatively high-pressure region in a gas, and the ion control field comprises pressure gradients.