FIXED-WAVELENGTH LASER IONIZATION TANDEM MASS-SPECTROMETRY FOR MIXTURE ANALYSIS IN THE QUADRUPOLE ION TRAP

The analytical potential of fixed-wavelength laser photoionization/tandem mass spectrometry in the quadrupole ion trap is investigated. The capability of the ion trap for mass-selective isolation and dissociation of laser-generated ions is exploited for organic mixture analysis. Despite the fact that collision-induced dissociation (CID) yields product ions no different from the fragment ions produced via laser ionization/fragmentation, tandem mass spectrometry is shown to improve the specificity of fixed-wavelength (266-nm), resonance-enhanced, two-photon ionization (R2PI). The technique is illustrated by using mass-selective CID of laser-generated molecular ions from a mixture of ethylbenzene, propylbenzene, and the isomers N,N-dimethylaniline and N-ethylaniline.