Hybrid Systems Involving Ion Traps

A number of hybrid tandem mass spectrometer systems, in which ion traps are involved, are commercially available. Ion traps can be apphed either in the first stage (MSI) or in the second stage (MS2) of mass analysis. 

In the (J-LIT hybrid [25] instruments, an ion trap is implemented as the second stage of mass analysis, either for accumulation of ions to achieve improved sensitivity after colhsion cell CID [25,46], and/or to perform MS [25,46,47]. The Q-LIT instrument can either be operated as a conventional TQ instrument or as the hybrid instrument. In TQ mode, the instrument is capable of all acquisition modes of a TQ, including SRM. In the hybrid mode, fidl-spectrum data can be acquired in the enhanced product ion (EPI) mode with up to 60-fold enhaneed sensitivity eompared to TQ instruments. Next to the enhanced multiple-charge sean and the time-delayed fragmentation scan, the system allows the acquisition of MS spectra, with the second dissociation step to be performed in the LIT [46,47]. 

This is true for ion trap hybrids with FT-ICR-MS (see Sect. 4.4.7) and Orbi-trap (see Sect. 4.4.9) instruments, but also for the ion trap-time-of-flight hybrid system. The latter system has been pioneered by the group of Lubman [87, 88]. It has become commercial available for both MALDI and LC-MS applications [89]. All these hybrid MS system are frequently applied in combination with LC and electrospray ionization in, for instance, drag metabolite identification studies and in various proteomics-related studies. 

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