Tandem Mass Spectrometry Using an Axially Resonant Excitation Linear Ion Trap

Abstract

We performed collision-induced dissociation (CID) and electron capture dissociation (ECD) analyses using a new ion trap: an axially resonant excitation linear ion trap (AREX LIT). Unlike a conventional linear ion trap, the AREX LIT can trap and detect low m/z fragment ions, such as immonium ions and iTRAQ^TM reporter ions, that are produced by CID. This capability to detect low m/z fragments is realized by CID excitation in a nearly harmonic direct current potential along the linear axis. In contrast, CID excitation in a conventional linear ion trap is in a pseudo-harmonic radio frequency potential that destabilizes fragment ions whose m/z is less than 1/4 that of the precursor ions. ECD was achieved in an axial magnetic field of about 0.2 Tesla superimposed along the AREX LIT. We observed that sequential ECD/CID inside the trap improved the sequence coverage of a peptide.