| abstract |
A method of obtaining a mass spectrum of elements in a sample is disclosed. Sample precursor ions having a mass-to-charge ratio M/Z are generated, and fragmented at a dissociation site, so as to produce fragment ions of mass to charge ratio m/z. The fragment ions are guided into an ion trap 130 of the electrostatic or 'Orbitrap' type, the fragment ions entering the trap in sub-groups dependent upon the precursor ions' M/Z. The mass-to-charge ratio of each sub-group is determined from the axial movement of ions in the trap. The electric field in the trap is then distorted. Ions of the same m/z, that are derived from different pre-cursor ions, are then separated because the field distortion 202 causes the axial movement to become dependent upon factors other than m/z alone. |