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

By applying different electric field strengths to the orifice-skimmer regio n of an electrospray ionization mass spectrometer, the rate of dissociation can be varied based on the amount of infernal energy acquired by an ion th rough collisions: with the curtain gas molecules. Both the Arrhenius equati on and Rice-Ramsperger-Kassel (RRK) theory can be used to predict the rate of dissociation of internally excited molecules. A previously determined mo del for collision-induced dissociation is tested by comparison of predicted and experimentally observed orifice-skimmer potential differences for diss ociation of ions. The rate of collision-induced dissociation of bradykinin ions is determined by monitoring the fragments produced in a mass spectrome ter. The semi-quantitative model is found to yield effective predictions wh en accurate Arrhenius and RRK parameters are utilized. (C) 2001 American So ciety for Mass Spectrometry.