FAIMS waveform

Equation 3.16. That is because only Equation 3.9 provides fixed E in both F+(f) and other F(t) comprise a range of E in at least one segment and thus are less asymmetric. So the rectangular F(t) with/of 2 or 3.7, depending on the amplitude constraint, was deemed the ideal FAIMS waveform. That is not accurate for two reasons. 

Though FAIMS waveforms of all classes have been implemented with various / values (1 for the rectangular, 2-A for bisinusoidal,and 2.9-4.8 for... 

Characteristics of FAIMS Waveforms of Three Common Classes Optimized with Ed Constraint for a E/N) Expansions Limited to the First Two Terms... 

The existence of different FAIMS waveform classes raises the issue of their relative merits. The optimum rectangular F(t) is always best (3.1.2) but is tougher to engineer than harmonic-based profiles (3.1.3), making one wonder about the magnitude of performance gain. 

So far, we have assumed FAIMS waveforms to follow the ordained U(t) dependence. The waveforms produced by real electronics always carry unwanted oscillations (electronic noise) of diverse physical origin, including thermal, shot, and inductive coupling of instmmental and environmental RF. Thermal ( white ) noise has uniform power spectrum that allows unbiased gauging of the impact of noise on FAIMS performance. Other noises appear over limited fiequency ranges ( pink noise) or at specific frequencies such as overtones of harmonics comprising Ed(0 or the industrial AC power frequency (60 Hz in USA) and its overtones. The spectra of those noises are sensitive to specific FAIMS hardware and lab environment. The effect of noise ceases above some frequency because ions have not enough time to respond. Based on the relaxation time estimates (3.2.1),... 

A kind of noise is ripple —a harmonic oscillation (of some frequency wr) that is much slower than FAIMS waveform but periodic on the separation timescale (i.e., 1/ res Wr [Pg.242]

So, if the imperfections of E t) he in that ballpark, the resolution would be near-independent of the ion current the postulated redistribution of ions in the gap (4.3.5), though continuous rather than periodic, may be caused by noise on the FAIMS waveform. However, other randomizing phenomena may be as or more important (4.3.5) and the origins of peak smearing in FAIMS remain uncertain. 

HOD IMS methods (5.2.1). The magnitude of necessary for HOD IMS analyses of order n depends on the a values for ions of interest (rigorously, on the spreads between for the species to be resolved, 3.1.7). The most extensive compilations of 02 values are the measurements for 17 amino acid cations and anions that we looked at in the context of FAIMS waveform optimization (3.1). In that set, the means (medians) are 6.8x10 (6.0x10 ) Td for a-[ and 1.5x10 ° for fl2 the similarity of means and medians for either suggests that the selection of a and 02 values is representative. ... 

DGE a AC AMS APCI API AP-MALDI APPI ASAP BIRD c CAD CE CF CF-FAB Cl CID cw CZE Da DAPCI DART DC DE DESI DIOS DTIMS EC ECD El ELDI EM ESI ETD eV f FAB FAIMS FD FI FT FTICR two-dimensional gel electrophoresis atto, 10 18 alternating current accelerator mass spectrometry atmospheric pressure chemical ionization atmospheric pressure ionization atmospheric pressure matrix-assisted laser desorption/ionization atmospheric pressure photoionization atmospheric-pressure solids analysis probe blackbody infrared radiative dissociation centi, 10-2 collision-activated dissociation capillary electrophoresis continuous flow continuous flow fast atom bombardment chemical ionization collision-induced dissociation continuous wave capillary zone electrophoresis dalton desorption atmospheric pressure chemical ionization direct analysis in real time direct current delayed extraction desorption electrospray ionization desorption/ionization on silicon drift tube ion mobility spectrometry electrochromatography electron capture dissociation electron ionization electrospray-assisted laser desorption/ionization electron multiplier electrospray ionization electron transfer dissociation electron volt femto, 1CT15 fast atom bombardment field asymmetric waveform ion mobility spectrometry field desorption field ionization Fourier transform Fourier transform ion cyclotron resonance... 

Kolakowski, B. M., Lustig, D., and Purves, R. W. (2004). Separation and quantitation of caffeine metabolites by high-field asymmetric waveform ion mobility spectrometry (FAIMS). 

Wu, S. T., Xia, Y. Q., and Jemal, M. (2007). High-field asymmetric waveform ion mobility spectrometry coupled with liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-FAIMS-MS/MS) multicomponent bioanalytical method development, performance evaluation and demonstration of the constancy of the compensation voltage with change of mobile phase composition or flow rate. Rapid Commun. Mass Spectrom. 21 3667-3676. 

Kolakowski, B.M., Mester, Z. (2007). Review of applications of high-field asymmetric waveform ion mohility spectrometry (FAIMS) and differential mobility spectrometry (DMS). Analyst 132 842-64. 

FAIMS high-field asymmetric-waveform ion-mobility spectroscopy... 

Krylov, E.V. Comparison of the Planar and Coaxial Field Asymmetrical Waveform Ion Mobility Spectrometer (FAIMS), Int. J. Mass Spectrom. 225, 39-51 (2003). 

FIGURE 6.5 Drift tubes for FAIMS or DMS including the configuration commercialized by Thermo Fisher Scientific (a) with a cylindrical shape (with permission from Thermo Fisher Scientific) the first small planar design commercialized by Sionex, Incorporated (b) (from Miller et al., A novel micro-machined high field asymmetric waveform ion mobility spectrometer, Sens. Actuators B 2000 with permission) and the microfabricated, very small structures of the ultraFAlMS (c) manufactured by Owlstone Nanotechnology (from Owlstone White Paper, 2006). 

Prieto, M. Tsai, C.W. Boumsellek, S. Ferran, R. Kaminsky, . Harris, S. Yost, R.A., Comparison of rectangular and bisinusoidal waveforms in a miniature planar FAIMS, Arud Chem. 2011, 83, 9237-9243. 

FIGURE 9.13 Schematic of ESI-FAIMS instrument interfaced to quadrupole mass spectrometer (QMS). (From Purves and Guevremont, Electrospray ionization high-field asymmetric waveform ion mobility spectrometry-mass spectrometry. Anal. Chem. 1999, 71(13) 2346-2357. With permission.)... 

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