Abstract: A method of operating a collision cell (10) in a mass spectrometer is disclosed. The collision cell comprises an entrance aperture (116), an exit aperture (117) and electrodes (113, 114) for producing electric fields. The method comprises feeding ions in a forward axial direction (LD) through the entrance aperture into the collision cell, producing a first electric field to trap ions, and subsequently producing a second electric field to accelerate trapped ions in the forward axial direction. The method further comprises producing a gas flow (G1) which is, at least at the entrance aperture (116) of the collision cell, contrary to the forward axial direction (LD), so as to reduce the kinetic energy of ions in dependence on their collisional cross sections. A collision cell arranged for carrying out the method is also disclosed, as well as a mass spectrometer comprising such a collision cell.

Abstract: An elemental mass spectrometer uses a mass filter to select ions from ions received from an ion source and transmit the selected ions. A reaction or collision cell receives the transmitted ions and reacts or collides these with a gas to provide product ions thereby. A mass analyzer receives the product ions, analyzes them and provides at least one output based on detection of the analyzed ions. The elemental mass spectrometer is operated to provide a first output from the mass analyzer measuring ions within a first analysis range of mass-to-charge to provide a second output from the mass analyzer measuring ions within a second analysis range of mass-to-charge ratios and to correct the first output for interference on the basis of the second output.