|An Advanced Cyclic Ion Mobility - Mass Spectrometry System
|Ion Mobility - Mass Spectrometry (BMSS)
|Dr Kevin Giles
|Dr Jakub Ujma
Mr Jason Wildgoose
Mr Martin Green
Dr Keith Richardson
Dr Nick Tomczyk
Abstract Information :
The powerful combination of ion mobility (IM) with mass spectrometry (MS) has generated a significant amount of interest from researchers operating over a broad range of subject areas. Whilst there is a notable focus on bringing this technology into more routine use, the need to further advance the capabilities of this hyphenated approach is ever present. In more recent years there has been considerable progress in the separative capability of sub-ambient pressure IM with resolutions in the many hundreds being demonstrated. One particular system is a travelling wave-enabled cyclic IM (cIM) separator embedded in a quadrupole time-of-flight (Q-ToF) MS instrument, which not only provides high resolution but also the capability for sequential IM separations. What will be presented here are the design and performance characteristics of a second generation Q-cIM-ToF system.
The base instrument comprising the second generation system is a Waters Synapt G2-Si (Q-IM-ToF) mass spectrometer. Compared to the first generation cIM system there have been enhancements to the ion optics, mass analyser, detection system and instrument control. The new cIM cell has the same 100 cm path length as the original design but is constructed of quadrants as opposed to a single element design, which makes it easier to manufacture. This new construct is found to perform as well as the previous version, with mobility resolution in excess of 500 being realised. Modifications to both the instrument control software and firmware for the multi-function array at the heart of the cIM have been undertaken. These enable excision and storage of segments of mobility separated ions to be carried out, followed by activation and re-analysis in the cIM device. As such, IMn analyses are possible. A quadrupole ion guide with axial field replaces the standard transfer cell and is used to transport ions from the cIM to the ToF; this both maintains the mobility separation and conditions the ion beam for high transmission into the ToF analyser. The ToF itself is of increased length compared to a standard instrument and has a novel offset V/W geometry. A maximum m/z resolution of around 120k has been obtained in the offset W-mode. A new, dual gain ADC detection system has also been implemented, providing up to 60x increase in dynamic range over the standard instrument and work is underway to provide increased mobility record length to account for the longer separation times in the cIM device.
The performance of this system will be highlighted with a range of samples from small molecules to proteins and protein complexes.