Ion-mobility spectrometry–mass spectrometry

Ion-mobility spectrometry–mass spectrometry (IMS-MS) is a method that is potentially able to rapidly separate components on a millisecond timescale using ion-mobility spectrometry and use mass spectrometry on a microsecond timescale to identify components within a test sample

History
Earl W. McDaniel has been called the father of ion mobility mass spectrometry. In the early 1960s, he coupled a low-field ion mobility drift cell to a sector mass spectrometer. The combination of time-of-flight mass spectrometry and ion-mobility spectrometry was pioneered in 1963 at Bell Labs. In 1963 McAfee and Edelson published an IMS-TOF combination. From their Letter to the Editor it is not conclusive whether they used an orthogonal extraction TOF. Most likely it was, because they seem to have used the TOF of the company Bendix, which was an orthogonal TOF. In 1967 McKnight, McAfee and Sipler published an IMS-TOF combination. Their instrument clearly included an orthogonal TOF. In 1969 Cohen et al. filed a patent on an IMS-QMS system. The QMS at that time was an improvement compared to the TOFMS, because the TOFMS lacked under the slowlyness of the electronic data acquisition systems at that time. In 1970, Young, Edelson and Falconer published an IMS-TOF with orthogonal extraction. They seem to have used the same system as McKnight et al. in 1967, incorporating slight modifications. Their work was later reproduced in the landmark book of Mason/McDaniel, which is regarded as the “bible of IMS” by those skilled in the art. In 1996 Guevremont et al. presented a poster at the ASMS conference about IMS-TOF. In 1997 Tanner patented a quadrupole with axial fields which can be used as a drift cell for IMS separation. He also mentions the combination of these quadrupoles with an orthogonal TOFMS. In 1998 Clemmer reinvented the IMS-TOF combination, using a co-axial IMS-TOF setup. In 1999 Clemmer reinvented the IMS-TOF with an orthogonal TOF system.

Instrumentation
The IMS-MS is a combination of an ion-mobility spectrometer and a mass spectrometer. First the ion mobility spectrometer separates ions according to their mobilities. In a second step the mass spectrometer separates ions according to their mass-to-charge ratio. Such a combination is often referred to as a hyphenated separation or multi-dimensional separation.

There are different types of ion mobility spectrometers and there are different types of mass spectrometers. In principle it is possible to combine every type of the former with any type of the latter.

Types of IMS-MS include TOFIMS (time-of-flight IMS) or the traditional ion mobility spectrometer, DMS differential mobility spectrometer, a scanable filter, also called FAIMS, and DMA differential mobility analyzer, a scanable filter.

Applications
The IMS-MS technique can be used for analyzing complex mixtures. It is used in proteomics for the analysis of peptides, detection of chemical warfare agents, detection of explosives, analysis of nano particles.