A SECTOR ION TRAP HYBRID MASS-SPECTROMETER OF BE TRAP CONFIGURATION

Substitution of a quadrupole ion trap for a quadrupole mass filter as a component of a hybrid mass spectrometer results in a new instrument of BE/trap configuration. Use of a small ion trap (radius 0.5 cm) gives an instrument in which the trap and sectors have similar mass ranges under stand operating conditions. Mass-selective instability scans of the ion trap provide daughter ion spectra for parent ions selected using the sectors and injected into the trap. Instrument performance, including resolution and signal-to-noise characteristics, is comparable in the ion injection mode to the performance in normal ion trap mass spectra recorded with internal ionization. Ions are activated in the course of injection as a result of both surface and gas-phase collisions. Collisions with surfaces are demonstrated by injecting noble gas ions and observing hydrocarbon ions generated by chemical sputtering from surfaces. Stable ions such as the pyrene molecular ion can easily be fragmented and the internal energy deposited is readily controlled through its dependence on the translational energy of the ion beam injected into the trap. The utility of the instrument for characterizing small peptides is illustrated. © 1990.