Collisionally activated dissociation of peptides using a quadrupole ion-trap mass spectrometer

The ion‐trap mass spectrometer can be used to record mass and multi‐stage tandem mass spectra (MSn) on small peptides. The compounds are ionized by Cs+ surface ionization, injected into the trap, mass selected, activated by collision, resulting in dissociation and mass‐selectively ejected. Tandem mass spectrometric data on sub‐fmol amounts of Gramicidin S are shown, along with tandem mass spectrometric and MSn data on two other peptides. The experiment is distinguished by its very high sensitivity and the high quality of sequence information obtained.