Field asymmetric waveform IMS

Recently, two other approaches to IMS have been introduced commercially these are high field asymmetric waveform IMS (FAIMS) [2] and traveling wave IMS (TWIMS) [3]. 

R.A. Miller, G.A. Eiceman, E.G. Nazarov and A.T. King, A micro-machined high-field asymmetric waveform-ion mobility spectrometer (FA-IMS), Sensor and Actuators B. Chemical, 67 (2000) 300—306. www.sionex.com (click to products)... 

E. G. Nazarov, and A. T. King, A Micro-Machined High-Field Asymmetric Waveform-Ion Mobility Spectrometer (FA-IMS), Sens. Actuators B Chem. 

Over the last decade, scientific and engineering interests have been shifting from canventional ion mobility spectrometry (IMS) to field asymmetric waveform ion mobility spectrometry (FAIMS). Differential Ion Mobility Spectrometry Nonlinear Ion Transport and Fundamentals of FAIMS explores this new analytical technology that separates and characterizes ions by the difference between their mobility in gases at high and low electric fields. It also covers the novel topics of higher-order differential IMS and IMS with alignment of dipole direction. 

This is the first book on differential ion mobility spectrometry (IMS), an analytical technique also called field asymmetric waveform ion mobility spectrometry (FAIMS) and, on occasion, several of the altemafive names mentioned in the Introduction. These terms refer to the evolving methods for separation and characterization of ions based on the nonlinearity of their motion in gases under the influence of a strong electric field. 

Mass spectrometrists have always been concerned with the measurement of the mass and intensity of analyte ions. Investigation/utilization of the shapes of molecules is now possible with ion mobility techniques that utilize differences in the cross sections of ions as they move through a gas. Think in terms of two pieces of paper, one crumpled and the other flat. If dropped at the same time, the crumpled one will hit the floor first because it will encounter less air resistance than the flat piece. A similar situation applies to ions with different shapes as they travel through a gas. Although ion mobility has been examined with home-built instruments for years, only recently has this type of analyzer become available commercially. There are two significantly different types, the high-field asymmetric waveform ion mobility spectrometer (FAIMS) and the ion mobility separator (IMS). The FAIMS separator is placed between the ion source and the analyzer, while the IMS cell is located between the analyzers of an MS/MS instrument. 

Ion-mobility may be implemented in IMS-MS systems in the form of (a) drift tubes, as already discussed [138, 139, 144], (b) differential ion-mobility or high-field asymmetric waveform ion mobility spectrometiy (FAIMS) devices [145-147], and (c) traveling-wave ion guide devices [44,148]. Tandem IMS-IMS-MS systems... 

Whereas high-field asymmetric waveform ion mobility spectrometry (FAIMS) is able to separate ions in a manner similar to IMS, the method cannot be considered an alternative to IMS in the context (elucidation of ion structure) discussed here, since electric fields employed in FAIMS are way above the low-field limit. " - However, two other newer developments, traveling-wave IMS and overtone ion mobility spectrometry (OMS), are worth mentioning here briefly. 

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