A mass spectrometer for analyzing isotopic signatures, with at least one magnetic analyzer and optionally with an electric analyzer as well, with a first arrangement of ion detectors and/or ion passages and, arranged downstream thereof in the direction of the ion beam, a second arrangement of ion detectors, with at least one deflector in the region of the two arrangements of ion detectors or between these arrangements. Additionally, a multi-collector arrangement, special uses and a method for analyzing isotopes in a sample. The mass spectrometer according to the invention has a control for the at least one deflector such that ion beams of different isotopes can be routed to at least one ion detector in the second arrangement.