Method to control space charge in a mass spectrometer

Patent metadata

Field	Value
Publication number	US-9318310-B2
Application number	US-201214131972-A
Country	US
Kind code	B2
Filing date	Jul 11, 2012
Priority date	Jul 11, 2011
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

A method for operating a mass spectrometer having an ion trap over a plurality of selected mass-to-charge ranges constituting an overall mass-to-charge range is disclosed. For each of the plurality of selected mass-to-charge ranges the method comprises filling the ion trap with fragmented ions of the selected mass-to-charge ranges, cooling the fragmented ions trapped in the ion trap for a first cooling period, applying an RF voltage and a resolving direct current voltage to the ion trap for eliminating any remaining fragmented ions outside the selected ion mass-to-charge range and retaining ions within the selected ion mass-to-charge range, cooling the retained ions in the ion trap for a second cooling period, and scanning the retained ions out of the ion trap and detecting the ions released therefrom.

First claim

The invention claimed is:

1. A method for operating a mass spectrometer for a plurality of selected mass-to-charge ranges, the mass spectrometer having an ion trap, the plurality of selected mass-to-charge ranges constituting an overall mass-to-charge range, for each of the plurality of selected mass-to-charge ranges the method comprising:
filling the ion trap with fragmented ions of the selected mass-to-charge ranges;
cooling the fragmented ions trapped in the ion trap for a first cooling period;
applying an RF voltage and a resolving direct current voltage to the ion trap for eliminating any remaining fragmented ions outside the selected ion mass-to-charge range and retaining ions within the selected ion mass-to-charge range;
cooling the retained ions in the ion trap for a second cooling period; and
scanning the retained ions out of the ion trap and detecting the ions released therefrom.

2. The method of claim 1 , wherein the resolving direct current voltage for each of the plurality of mass-to-charge windows has a value dependent on the selected ion mass-to-charge range of each of the plurality of mass-to-charge windows.

3. The method of claim 2 , wherein the value of the resolving direct current voltage for each of the plurality of mass-to-charge windows is determined for destabilizing fragmented ions outside than the selected ion mass-to-charge range for each of the plurality of mass-to-charge windows.

4. The method of claim 1 , wherein the values of the RF voltage are selected to destabilize fragmented ions having m/z values outside the desired ion mass-to charge range.

5. The method of claim 1 , wherein the mass spectrometer has a triple quadrupole configuration having a first, second, and third quadrupole rod sets, the third quadrupole rod set configured as an ion trap.

6. The method of claim 1 , wherein the mass spectrometer has a double quadrupole configuration having a first and second quadrupole rod sets, the first quadrupole rod set configured as mass filter, the second quadrupole rod set configured as a collision cell for fragmenting ions, after fragmenting, fragmented ions returning to the first quadrupole rod set reconfigured as an ion trap.

7. The method of claim 1 , wherein mass spectra are obtained from the scanning steps of each of the plurality of mass-to-charge windows.

8. The method of claim 7 , wherein an overall mass spectrum is obtained for the overall mass-to-charge range by adding the mass spectra obtained from the scanning steps of each of the plurality of mass-to-charge windows.

Assignees

• Guna Mircea
• Dh Technologies Dev Pte Ltd

Inventors

• Guna Mircea

Classifications

• H01J49/427

  Ejection and selection methods · CPC title

• H01J49/422

  Two-dimensional RF ion traps (ion guides without mass selection H01J49/062) · CPC title

• H01J49/4265 Primary

  Controlling the number of trapped ions; preventing space charge effects · CPC title

• H01J49/004

  Combinations of spectrometers, tandem spectrometers, e.g. MS/MS, MSn · CPC title