Electron capture dissociation in a radio frequency ion trap.

We report on the first evidence of electron capture dissociation (ECD) in a radio frequency (rf) ion trap. Peptide ions, [substance P]2+, trapped in a two-dimensional, linear rf ion trap were cleaved by electrons injected along the central axis of the trap. Along the axis, the rf field component was zero and a magnetic field of 50 mT was applied. This electron injection scheme keeps the energy of the electrons below 1 eV, preventing them from heating by the rf field. The present ECD efficiency is approximately 4% by irradiation of electron current of 0.2 microA for 80 ms. ECD in rf traps may open high-throughput and low-cost ECD applications to obtain molecular structure information complementary to collision-induced dissociation.