Method of detecting ions in an ion trap mass spectrometer
AssigneeFinnigan Corporation
InventorsJae C. Schwartz, John N. Louris
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Abstract
A method is disclosed for operating an ion trap mass spectrometer in such a way as to distinguish resonantly ejected ions from non-resonantly ejected ions. A supplementary AC field is superimposed on the three-dimensional quadrupole trapping field and the combined fields are scanned to resonantly eject ions of consecutive mass-to-charge ratio. The ejected ions are detected and the output signal of the resonantly ejected ions has a frequency component at the frequency of the supplementary AC field.
Claims18
The method of operating an ion trap mass spectrometer comprising the steps of
- defining a trap volume with a three-dimensional substantially quadrupole field for trapping ions within a predetermined range of mass-to-charge ratio,
- forming within or injecting ions into said trap volume such that those within said predetermined mass-to-charge ratio range are trapped,
- applying a supplementary AC field superimposed on said three-dimensional quadrupole field to form combined fields,
- changing said combined fields to sequentially resonantly eject ions from said trap volume for detecting ejected ions and generating an output signal in which the output signal of said resonantly ejected ions has a frequency component at the frequency of said supplementary AC field.
The method of operating an ion trap mass spectrometer in the mass selective instability mode with resonance ejection which comprises
- applying a supplementary AC field at a selected frequency, whereby the resonantly ejected ions have an ejection frequency component at said selected frequency,
- detecting the ejected ions and providing an output signal which includes a component having said selected frequency to identify said resonantly ejected ions.
The method of operating an ion trap in the mass selective instability mode with resonant ejection of ions which comprises detecting all ejected ions including resontantly ejected and non-resonantly ejected ions, and identifying the resonantly ejected ions.
The method of operating an ion trap mass spectrometer comprising the steps of
- defining a trap volume with a three-dimensional substantially quadrupole field for trapping ions within a predetermined range of mass-to-charge ratio,
- forming within or injecting ions into said trap volume such that those within said predetermined mass-to-charge ratio range are trapped,
- applying at least two supplementary AC fields at different frequencies superimposed on said three-dimensional quadrupole field to form combined fields,
- changing said combined fields to sequentially resonantly eject ions from said trap volume for detecting ejected ions and generating an output signal in which the output signal of said resonantly ejected ions has a frequency component at the frequency of at least one of said supplementary AC fields.
The method of operating an ion trap mass spectrometer comprising the steps of
- defining a trap volume with a field for trapping ions within a predetermined range of mass-to-charge ratio,
- forming or injecting ions within said trap volume such that those within said predetermined mass-to-charge ratio range are trapped,
- applying a supplementary AC field superimposed on said field to form combined fields,
- changing said combined fields to sequentially resonantly eject ions of consecutive mass-to-charge ratio from said trap volume for detecting ejected ions and providing an output signal in which the output signal of said resonantly ejected ions has a frequency component at the frequency of said supplementary AC field.
The method of operating an ion trap mass spectrometer comprising the steps of
- defining a trap volume with a field for trapping ions within a predetermined range of mass-to-charge ratio,
- forming or injecting ions within said trap volume such that those within said predetermined mass-to-charge ratio range are trapped,
- applying at least two supplementary AC fields at different frequencies superimposed on said field to form combined fields,
- changing said combined fields to sequentially resonantly eject ions of consecutive mass-to-charge ratio from said trap volume for detecting ejected ions and providing an output signal in which the output signal of said resonantly ejected ions has a frequency component at the frequency of said supplementary AC field.
Dependencies are inferred from the claim text.