Collision-induced dissociation of bradykinin ions in the interface region of an ESI-MS

By applying different electric field strengths to the orifice-skimmer region of an electrospray ionization mass spectrometer, the rate of dissociation can be varied based on the amount of internal energy acquired by an ion through collisions with the curtain gas molecules. Both the Arrhenius equation and Rice-Ramsperger-Kassel (RRK) theory can be used to predict the rate of dissociation of internally excited molecules. A previously determined model for collision-induced dissociation is tested by comparison of predicted and experimentally observed orifice-skimmer potential differences for dissociation of ions. The rate of collision-induced dissociation of bradykinin ions is determined by monitoring the fragments produced in a mass spectrometer. The semi-quantitative model is found to yield effective predictions when accurate Arrhenius and RRK parameters are utilized.