The Pentafluoro-Tropylium Ion as a Proton Donor in the Internal Ionization Quadrupole Ion Trap

摘要

The possibility of ion-molecule reactions in the Internal Ionization Quadrupole Ion Trap (I~(2)QIT) exists when El fragmentation yields good proton donors in the presence of analytes possessing high proton affinity. This phenomenon of "Self Chemical Ionization (CI)" is an acknowledged result of ion storage times being equal to thousands of microseconds in the QIT as opposed to tens of microseconds in the transmission quadrupole. This has been reported as both useful (eg. identifying cyclic vs. unsaturated olefins; Lassman et. al., 2002) and as a general nuisance (eg. for carbonyl compounds containing gamma hydrogens; Sparkman, 1997). In the case described here, except for the molecular ion's mass shift, very little difference in the mass spectral quality was observed when the QIT spectrum was compared to a literature report of the transmission quadrupole spectrum. All MS/MS analyses were done on a Saturn 2000 GC/MS system (Varian Instruments), equipped with an autoinjector in the Solid Phase Microextraction (SPME) mode. Sample preparation was done using a SPME on-fiber process described previously (Martos and Pawliszyn, 1998). Samples were chromatographed on a 30 meter X 250 micron DB-5 MS column with 0.25 micron film thickness (J&W Scientific).