MULTIPLE STAGES OF MASS-SPECTROMETRY IN A QUADRUPOLE ION TRAP MASS-SPECTROMETER - PREREQUISITES

The number of stages of mass spectrometry that can be performed with a quadrupole ion trap is discussed. The conditions necessary, both instrumental and chemical, to maximize the number of stages are delineated. The overall efficiency of the MS(n) experiment is broken down into the isolation efficiency of the initial parent ion, the conversion efficiencies associated with the conversion of first generation parents to second generation parents, and so on, and the efficiency of the final step which yields the final product ions. The conversion efficiencies are further broken down into component terms that reflect both instrumental and chemical factors. Both collision-induced dissociation reactions and low energy ion/molecule reactions are discussed. These considerations are illustrated with MS(n) experiments involving ions derived from aniline, N,N-dimethylaniline, and several porphyrins.