Method and device for controlling the number of ions in ion cyclotron resonance mass spectrometers
AssigneeBrucker Daltonik GmbH
InventorsGökhan Baykut, Jochen Franzen
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Abstract
The invention relates to a method and a device for controlling the number of ions in ion cyclotron resonance (ICR) mass spectrometers, whereby the ions enter a multipole ion guide after their formation and are stored there temporarily. By measuring the ion number in a predefined subset of these temporarily stored ions, the number of ions transferred into the ICR trap for mass spectrometric analysis is regulated. A mode of operation of the multipole ion guide can ensure that undesirable mass ranges are filtered out before the transfer of ions into the ICR mass spectrometer. The invention makes it possible to eliminate space charge effects, which are caused by overfilling the ICR traps.
Claims20
A method for controlling the filling of an ion trap of an ion cyclotron resonance mass spectrometer with a desired quantity of ions, the method comprising:
- storing the ions in a multipole ion guide;
- measuring a defined subset of the temporarily stored ions to determine an approximate filling level of the ion guide;
- and
- transferring at least a portion of the ions from the ion guide to the ion trap, a size of the transferred portion being determined from the measured approximate filling level.
A device for temporarily storing ions formed by laser desorption of a sample on a sample carrier plate, the device comprising:
- a multipole ion guide located in front of the carrier plate;
- an apertured end plate located to a side of the ion guide opposite the end plate;
- a measurement apparatus for measuring a subset of the ions stored in the ion guide and determining an approximate filling level thereof;
- and
- a switchable potential supply electrically connected to the apertured plate, wherein the potential supply may be switched between a first potential that reflects the ions into the ion guide and a second potential that extracts the ions from the ion guide, a duration of the switching to the second potential being in response to the measured approximate filling level.
Dependencies are inferred from the claim text.