Ion trap mass spectrometer system and method
First Claim
1. An ion trap mass spectrometer for analyzing ions comprising:
- a trapping chamber including at least two electrodes shaped to promote an enlarged ion occupied volume, the trapping chamber having a center axis;
means for establishing and maintaining a substantially quadrupole field in the trapping chamber to trap ions within a predetermined range of mass-to-charge ratios;
means for introducing or forming ions in the trapping chamber where the ions are trapped by the substantially quadrupole field;
means for changing the substantially quadrupole field so that the trapped ions of specific masses become unstable and leave the trapping chamber in a direction orthogonal to the center axis;
means for detecting ions after the ions leave the structure; and
means for providing an output signal indicative of the mass-to-charge ratio of the detected ion.
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Abstract
The present invention relates generally to an ion trap mass spectrometer for analyzing ions and more particularly to a substantially quadrupole ion trap mass spectrometer with an enlarged ion occupied volume. Described herein are electrode geometries that enlarge the ion occupied volume. Improved ion sensitivities, detection limits and dynamic range should be realized for the same charge density in these devices because the increased ion occupied volume allows for the storage of a greater number of ions. The essence of this invention is that these ion trap geometries may apply all modes of operation of substantially quadrupole ion traps such as the mass selective instability mode, resonance excitation/ejection, and MSn.
327 Citations
29 Claims
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1. An ion trap mass spectrometer for analyzing ions comprising:
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a trapping chamber including at least two electrodes shaped to promote an enlarged ion occupied volume, the trapping chamber having a center axis; means for establishing and maintaining a substantially quadrupole field in the trapping chamber to trap ions within a predetermined range of mass-to-charge ratios; means for introducing or forming ions in the trapping chamber where the ions are trapped by the substantially quadrupole field; means for changing the substantially quadrupole field so that the trapped ions of specific masses become unstable and leave the trapping chamber in a direction orthogonal to the center axis; means for detecting ions after the ions leave the structure; and means for providing an output signal indicative of the mass-to-charge ratio of the detected ion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A method of scanning ions in an ion trap mass spectrometer, comprising the steps:
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establishing and maintaining a substantially quadrupole field in which ions within a predetermined range of mass-to-charge ratios can be trapped in the trapping chamber; introducing ions in the trapping chamber wherein ions within the predetermined range of mass-to-charge ratios are trapped; creating an enlarged ion occupied volume without an increase in space charge within a trapping chamber; changing the substantially quadrupole field so that the trapped ions of specific mass-to-charge ratios become unstable and leave the trapping chamber in a direction substantially orthogonal to a center axis; detecting the unstable ions after they leave the trapping chamber; and providing an output signal indicative of ion mass-to-charge ratio.
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Specification