Ion trap mass spectrometer using pre-calculated waveforms for ion isolation and collision induced dissociation
AssigneeVarian, Inc.
InventorGregory J. Wells
Life of this patent
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Abstract
In a quadrupole ion trap mass spectrometer, a library of optimized notched waveforms are pre-calculated, optimized and stored in a fast memory such as semiconductor RAM. Computer controlled apparatus selectively applies the pre-calculated waveforms to end caps of the quadrupole ion trap for isolating an ion with a specific mass to charge ratio. The pre-calculated waveforms are optimized notch waveforms with each waveform being pre-calculated for a specific mass. The memory further stores a library of single frequency CID waveforms for use in collision induced dissociation of an isolated ion. By providing the pre-calculated waveforms, a method is provided to isolate and dissociate a selected ion.
Claims19
A quadrupole ion trap for use in a mass spectrometer comprising:
- a) a ring electrode,
- b) a pair of end caps,
- c) an RF trapping voltage source for applying a trapping voltage to the ring electrode, and
- d) computer controlled apparatus for selectively applying pre-calculated waveforms to the end caps for isolating an ion with a specific mass to charge ratio.
In a quadrupole ion trap mass spectrometer having a ring electrode, a pair of end caps, an RF trapping generator, the improvement comprising:
- computer controlled apparatus for selectively applying pre-calculated waveforms to the end caps for isolating an ion with a specific mass to charge ratio.
In a method of isolating a selected parent ion having a mass, M, for MS/MS spectrometry employing a quadrupole ion trap (QIT), said QIT having a ring electrode, a pair end caps, an RF trapping voltage source for applying the trapping voltage to the ring electrode, and an RF voltage source connected to the end caps, said method including the steps of:
- a) storing pre-calculated waveforms for isolating ions of specific mass to charge ratios, and
- b) selectively applying a pre-calculated waveform to the end caps for isolating an ion with specific mass to charge ratio.
Dependencies are inferred from the claim text.