Abstract: The invention relates to a method and a mass spectrometer for mass spectroscopic or mass spectrometric investigation of particles. The particles are separated in a separating system in accordance with their different masses. In order to reduce detection errors due to scattered particles, there is arranged upstream of a detecting device a correction device which builds up a braking potential in order to suppress particles having an energy loss due to scattering. The invention provides a further, preferably combined correction, by means of which the particles are selected as a function of their direction of motion. For this purpose, the mass spectrometer according to the invention preferably has at least one braking electrode and one quadrupole lens.

Abstract: In isotope mass spectrometry, there is the problem that in the case of very great frequency differences, the less frequent masses are swamped by the more frequent masses in the measurement result or that the corresponding measurement result is falsified. A correction device is proposed, which comprises a quadrupole mass filter with a voltage supply device which is controlled by the ion separation system and is designed in such a manner that the supply voltages of the quadrupole mass filter and thus its characteristic with respect to the mass quantity to be allowed through are switched over synchronously with the varying mass deflection setting of the ion separation system.