Patent ID: 6147348
Filing Date: 2000-11-14
Classification: H01J

Abstract:
A method for performing a scan function on a quadrupole ion trap, comprising the following steps:a) trapping sample ions in the ion trap;b) obtaining a mass spectrum of the sample ions;c) selecting and storing the mass-to-charge ratios of the ions which are present and/or meet at least one predetermined criterion;d) trapping additional sample ions in the trap;e) ejecting all ions with mass-to-charge ratios below the lowest stored mass-to-charge ratio;f) resonantly exciting ions of the lowest stored mass-to-charge ratio;g) performing a mass-selective instability scan over a mass-to-charge ratio range of interest;h) ejecting all ions with mass-to-charge ratios below the next lowest stored mass-to-charge ratio;i) resonantly exciting ions of the next lowest stored mass-to-charge ratio;j) performing a mass-selective instability scan over a mass-to-charge ratio range of interest; andk) repeating steps h, i, and j until ions of all stored mass-to-charge ratios have been resonantly excited,wherein the scan provides information about the sample ions.