Traveling Wave Ion Mobility MS

FIGURE 9.6 Schematic of a traveling wave ion mobility-mass spectrometer. (Available at http //pubs.acs.org/cen/coverstory/86/8637cover.html/. With permission.) 

After mobility separation, ions are transferred to a third traveling wave cell similar to the first cell of the triwave assembly and operating as an ion transfer lens or as a CID cell. Finally, the ions are transferred into a high-resolution TOF-MS. Thus, many types of analyses can be performed with this single instrument. It can operate simply as an IMS-TOF or a Q-TOF, but it can also operate as a Q-IMS-TOF or, in its most powerful mode, as a Q-IMS-CID-TOF. 

The resolving power of the TW-IMS in the first-generation Synapt was only about 10. In the second generation, the TW-IMS resolving power has been significantly 

FIGURE 9.7 A two-dimensional plot of ion arrival time versus m/z for a protein digest mixture obtained using TW-IMS. (Reprinted from Pringle et al., An investigation of the mobility separation of some peptide and protein ions using a new hybrid quadrupole/travelling wave IMS/oa-ToF instrument, Int. J. Mass Spectrom. 2007, 261,1-12. With permission.) 

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For calculating relative collision cross sections using traveling wave ion mobility-MS, there are two main procedures used which can be found in the literature (29, 30). 

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