Ion Mobility oTOF Mass Spectrometers

The high-mobility ions have kept up with the wave and the low mobility ions have rolled over the top. Reproduced with permission from Ref. [117]. 

The typical time bin of an ion mobility separation is in the millisecond range. Because this time window is substantially larger than the duration of the TOF measuremenL many single mass spectra can be recorded during one IMS separation. Under optimal conditions the overall transmission efficiency is close to that achieved without IMS. Depending on the complexity of the sample, limits of detection in the subfemtomolar range are achieved in the MALDI-IMMS analysis of peptides. 

In the Synapt, the MALDI ions are generated at a fine vacuum of about 0.1 mbar and transferred via a hexapole ion guide into a stepwave ion guide. The step-wave serves to reduce the background of neutral particles, because only ions are lifted onto the ion axis of the mass spectrometer. An initial selection of ions of interests is achieved with a quadrupole preceding the trap cell. For most standard applications a m/z range of up to 4000 or 8000 Da can be selected, depending on 

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