FAIMS--Kristian Swearingen, Michael Hoopmann, and Robert Moritz (PI)
What is FAIMS?
High Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) is an established technology with a myriad of potential applications for augmentation of mass spectrometry. Although discovered and characterized for use with mass spectrometry by Gorshkov in the early 1980's, FAIMS technology has recently seen a marked increase in interest and innovation through the work of Roger Guevremont, Alexandre Shvartsburg, Richard Smith, and others. Thermo Fisher released a commercially available FAIMS interface for their ion trap mass spectrometers in 2007, and Agilent Technologies, Inc. and Owlstone Nanotech, Inc. announced in 2009 that they would cooperate to incorporate Owlstone's FAIMS-on-a-chip device into Agilent TOF systems.
What FAIMS Does and How it Works
FAIMS exploits the properties of gas phase ions in an oscillating field at atmospheric pressure. Ion mobility changes non-linearly with the strength of the electric field and is dependent on the charge and collisional cross section of the ion. In FAIMS, a stream of gas-phase ions is passed through a narrow gap between two electrode plates (in the case of the Thermo FAIMS, the two electrodes are concentric cylinders). The electric field between these two electrodes oscillates between a high voltage of one polarity and a low voltage of the opposite polarity. The term "asymmetric" in High Field Asymmetric Waveform Ion Mobility Spectrometry refers to the fact that the high-field portion of the waveform has a significantly shorter duration and greater magnitude than the opposite polarity low-field portion. The result is that a gas-phase ion will migrate toward one electrode during the high-field portion of the wave form and toward the opposite electrode during the negative portion of the waveform, but the distance travelled will differ between the high-field and low-field portions depending on the ion's mobility in the conditions within the FAIMS unit. Oscillating in this fashion, only ions with certain characteristics entering the FAIMS unit will avoid colliding with one electrode or the other and actually exit to pass on to the mass spectrometer. An additional parameter, a DC potential referred to as compensation voltage (CV) applied to the electrodes allows the user to tune the FAIMS unit and select which types of ions will be filtered out and which will be allowed to pass through.
As part of the development of FAIMS for high-resolution analysis of peptide dissociation using collision-induced dissociation (CID) and electron transfer dissociation (ETD) funded by the National Science Foundation (Award 0923536: MRI-Consortium: Development of ion mobility enhanced electron transfer dissociation for elucidating biological networks using a systems biology approach), we are working with Thermo-Fisher to modify and characterize a FAIMS device to deliver a stable, robust, and highly sensitive nano probe FAIMS interface for high sensitivity proteomic experiments. Coupling FAIMS with mass spectrometry will confer several advantages for proteomic research. For example, the FAIMS device can be tuned to allow only ions of interest to enter the mass spectrometer, thereby deflecting singly charged and contaminant ions and significantly increasing the signal-to-noise within the ion trap. Additionally, desirable charge states can be selected for, such as +2 ions for CID or higher charge states for ETD.
References, Links, and Useful Information
A. A. Shvartsburg, W. F. Danielson and R. D. Smith, "High-resolution differential ion mobility separations using helium-rich gases", (2010) 82, 2456-62
A. A. Shvartsburg, K. Tang, R. D. Smith, M. Holden, M. Rush, A. Thompson and D. Toutoungi, "Ultrafast differential ion mobility spectrometry at extreme electric fields coupled to mass spectrometry", (2009) 81, 8048-53
J. Saba, E. Bonneil, C. Pomies, K. Eng and P. Thibault, "Enhanced sensitivity in proteomics experiments using FAIMS coupled with a hybrid linear ion trap/Orbitrap mass spectrometer", (2009) 8, 3355-66
S. T. Wu, Y. Q. Xia and M. Jemal, "High-field asymmetric waveform ion mobility spectrometry coupled with liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-FAIMS-MS/MS) multi-component bioanalytical method development, performance evaluation and demonstration of the constancy of the compensation voltage with change of mobile phase composition or flow rate", (2007) 21, 3667-76
B. M. Kolakowski and Z. Mester, "Review of applications of high-field asymmetric waveform ion mobility spectrometry (FAIMS) and differential mobility spectrometry (DMS)", (2007) 132, 842-64
K. Venne, E. Bonneil, K. Eng and P. Thibault, "Improvement in peptide detection for proteomics analyses using NanoLC-MS and high-field asymmetry waveform ion mobility mass spectrometry", (2005) 77, 2176-86
A. A. Shvartsburg, K. Tang and R. D. Smith, "Optimization of the design and operation of FAIMS analyzers", (2005) 16, 2-12
R. Guevremont, "High-field asymmetric waveform ion mobility spectrometry: a new tool for mass spectrometry", (2004) 1058, 3-19
R. Guevremont, D. A. Barnett, R. W. Purves and J. Vandermey, "Analysis of a tryptic digest of pig hemoglobin using ESI-FAIMS-MS", (2000) 72, 4577-84
Shvartsburg, A. Differential ion mobility spectrometry: nonlinear ion transport and fundamentals of FAIMS CRC Press (2009)