Titelaufnahme

The formation of radical anions of nitroimidazolic radiosensitizers, nimorazole and metronidazole, and their unimolecular dissociation reactions upon high-energy collisions with He gas were investigated with a double focusing mass spectrometer equipped with an electrospray ionization (ESI) source. Radical anions of both, nimorazole and metronidazole, are readily formed in the ESI process, while for the metronidazole also the deprotonated anion is formed. A variety of dissociation channels is observed and the associated kinetic energy released in the dissociation for most of these channels is reported. The marker anion NO2− is observed in the dissociation of all studied anions. The release of NOradical dot radical from the radical anions is associated with surprisingly small kinetic energy release in comparison to simple nitroimidazoles. On the other hand, the highest kinetic energy release is noted for the release of the neutral side group from N1 position of the imidazole ring, which suggests that the substitution at the N1 plays a crucial role in the decomposition of anions of radiosensitizers.