The effect of ion trap temperature on the dissociation of peptide ions in a quadrupole ion trap

Thermally-assisted collision-induced dissociation can substantially increase the amount of dissociation in quadrupole ion trap mass spectrometer experiments. The experiments discussed here were performed to assess the effect on dissociation pathways as the bath gas temperature is increased in thermally-assisted collision-induced dissociation (TA-CID) experiments. Double resonance experiments in which a product ion was ejected during collision-induced dissociation of the parent ion provided data to asses competitive versus consecutive dissociation pathways. Consecutive dissociation pathways are indicated when lower mass product ions decrease in intensity when a higher mass product ion is ejected during CID. For the peptide ions studied, those that dissociate to give predominately N-terminal product ions show increased consecutive dissociation with increased temperature during TA-CID. For peptide ions that dissociate via formation of C-terminal product ions, competitive dissociation pathways were more prevalent and increasing the temperature had much less effect. N-terminal product ions consecutively dissociate to smaller N-terminal ions whereas C-terminal product ions dissociate to internal fragments. (C) 2010 Elsevier B.V. All rights reserved.