Field Dependence of Mobilities for Gas-Phase-Protonated Monomers and Proton-Bound Dimers of Ketones by Planar Field Asymmetric Waveform Ion Mobility Spectrometer (PFAIMS)

Krylov, Evgeny V.; Eg, Nazarov; Ra, Miller; Tadjikov, B.M.; Ga, Eiceman

doi:10.1021/jp020009i

Cited by 121 publications

(174 citation statements)

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“…6,7,16 While this increases the apparent 2-D peak capacity of IMS/MS, the correlation between ion mobility and mass is a fundamental limitation of IMS/MS methodology. This limitation has been one driver behind the recent development of Field Asymmetric waveform IMS (FAIMS), 13,14,[30][31][32][33] which separates ions by differential mobility as a function of electric field using a time-dependent field E(t). In this field, an ion drifts with the mean velocity: (4) The limits of integrals below are also t 0 and (t 0 + Δt), but are dropped for conciseness.…”

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Feasibility of Higher-Order Differential Ion Mobility Separations Using New Asymmetric Waveforms

2006

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Technologies for separating and characterizing ions based on their transport properties in gases have been around for three decades. The early method of ion mobility spectrometry (IMS) distinguished ions by absolute mobility that depends on the collision cross section with buffer gas atoms. The more recent technique of field asymmetric waveform IMS (FAIMS) measures the difference between mobilities at high and low electric fields. Coupling IMS and FAIMS to soft ionization sources and mass spectrometry (MS) has greatly expanded their utility, enabling new applications in biomedical and nanomaterials research. Here, we show that time-dependent electric fields comprising more than two intensity levels could, in principle, effect an infinite number of distinct differential separations based on the higher-order terms of expression for ion mobility. These analyses could employ the hardware and operational procedures similar to those utilized in FAIMS. Methods up to the 4 th or 5 th order (where conventional IMS is 1 st order and FAIMS is 2 nd order) should be practical at field intensities accessible in ambient air, with still higher orders potentially achievable in insulating gases. Available experimental data suggest that higher-order separations should be largely orthogonal to each other and to FAIMS, IMS, and MS.Approaches to separation of ion mixtures and characterization of ions in the gas phase based on ion mobility are becoming commonplace in analytical chemistry. The key advantage of gas-phase separations over condensed phase methods is the exceptional speed enabled by rapid molecular motion in gases. This inherent benefit is made increasingly topical by the growing focus of analytical technology on higher throughput. Since their first demonstration a decade ago, 1-3 instrumental platforms combining electrospray ionization (ESI) or matrixassisted laser desorption ionization (MALDI) sources with ion mobility separations and mass-spectrometry (MS) have undergone a sustained development that has improved their resolution and sensitivity to the levels demanded by practical applications. 4-10 Recent commercial introduction of such systems 11-14 is expanding interest in ion mobility/MS, particularly for analyses of complex biological samples such as proteolytic digests and lipids, nucleotides, and metabolites. [15][16][17][18][19][20][21][22][23][24] Single-stage ion mobility spectrometry (IMS) was investigated since the 1970s, 25-27 with a noteworthy development of ESI/IMS in 1980s. 28 In IMS, ions drift through a non-reactive buffer gas under the influence of a modest electric field. The drift velocity (v) in the field of intensity E is determined by ion mobility (K):(1)For consistency, measured mobilities are normally converted to reduced values K 0 by adjusting the buffer gas temperature (T, Kelvin) and pressure (P, Torr) to standard (STP) conditions:NIH Public Access

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“…Scanning E C produces a spectrum of the ion mixture. 49 Fundamentally, the value of a is not related to m as closely as K(0); in particular, a may be both positive and negative, 33 while K is always positive. As a result, FAIMS is generally more orthogonal to MS than IMS.…”

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Feasibility of Higher-Order Differential Ion Mobility Separations Using New Asymmetric Waveforms

2006

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“…For species with a 1 Ͼ 0, typically a 2 Ͻ 0, and a increases up to a maximum at certain E/N and decreases at greater E/N. This behavior (called "type B") [5] is ubiquitous for both atomic and polyatomic cations and anions with m Ͻ ϳ400 Da in N 2 or air at room temperature, including 13 of 17 protonated and 15 of 17 deprotonated amino acids [54], protonated benzene, and all seven amines studied [55], eight protonated ketones up to decanone and five of their proton-bound dimers [56], all 10 protonated organophosphorus compounds investigated and seven of their dimers [57], and I Ϫ and anions of five common explosives and their degradants: 1,3-dinitrobenzene, 1,3,5-trinitrobenzene, p-mononitrotoluene, 2,4-dinitrotoluene, and 2,4,6-trinitrotoluene (TNT) [28]. The magnitude of a 2 /a 1 for those 72 species spans Ͼ3 orders of magnitude from Ͻ10 Ϫ6 to Ͼ10 Ϫ3 Td Ϫ2 ( Figure 5), but most values are about 10 Ϫ5 to 10 Ϫ4 Td Ϫ2 regardless of the ion mass.…”

Section: Global Separationsmentioning

confidence: 96%

“…[54], protonated benzene and amines (crosshair) [55], protonated ketone monomers (filled circle) and dimers (open circle) [56], protonated monomers (filled square), and dimers (open square) of organophosphorus compounds [57], and deprotonated or radical anions of explosives (open diamond) [28]. Horizontal lines mark values providing a R ϭ Ϫ1 at the stated E/N.…”

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Optimum waveforms for differential ion mobility spectrometry (FAIMS)

Shvartsburg

Smith

2008

J. Am. Soc. Mass Spectrom.

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Differential mobility spectrometry or field asymmetric waveform ion mobility spectrometry (FAIMS) is a new tool for separation and identification of gas-phase ions, particularly in conjunction with mass spectrometry. In FAIMS, ions are filtered by the difference between mobilities in gases (K) at high and low electric field intensity (E) using asymmetric waveforms. An infinite number of possible waveform profiles make maximizing the performance within engineering constraints a major issue for FAIMS technology refinement. Earlier optimizations assumed the non-constant component of mobility to scale as E 2 , producing the same result for all ions. Here we show that the optimum profiles are defined bl the full series expansion of K(E) that includes terms beyond the first that is proportional to E . For many ionlgas pairs, the first two terms have different signs, and the optimum profiles at sufficiently high E in FAIMS may differ substantially from those previously reported, improving the resolving power by up to 2.2 times. This situation arises for some ions in all FAIMS systems, but becomes more common in recent miniaturized devices that employ higher E. With realistic K(E) dependences, the maximum waveform amplitude is not necessarily optimum, and reducing it by up to~20% to 30% is beneficial in some cases. In DMS, a(EIN) is elicited directly using a periodic time-dependent electric field E(t) that comprises short segments E+(t) with high E and longer segments L(t) with lower E of opposite polarity such that mean E over the period t c is null (the zero-offset condition) [33, 39-43]:D ifferential ion mobility spectrometry (DMS) is becoming a powerful method of broad utility for analysis of gas-phase ions and separation of their mixtures [1][2][3][4][5]. The introduction of commercial DMS instruments and particularly their integration with mass spectrometry (MS) andI or liquid or gas chromatography since 2003 has enabled rapid growth of the number and diversity of applications that include environmental analyses [6,7], food and water quality assurance [8][9][10], bacterial typing [11,12], forensic investigations [13], proteomics and metabolomics [14][15][16][17], pharmaceutical studies [18][19][20], and protein folding research [21][22][23][24][25]. Since its earliest days, DMS has been employed to detect explosives, drugs, and chemical warfare agents, and its role in defense, security, and law enforcement settings continues expanding [26][27][28][29][30][31].As captured by the name, DMS separates ions based on the difference between their mobilities (K) at high and relatively low electric field intensity (E) [1,5]. The mobility of any ion depends on E and the gas number density (N), and we can expand K(EIN) in a series [7,30,32,33]:

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Differential Mobility Spectrometry and Its Application to High‐Throughput Analysis

Schneider¹,

Bedford²,

Liu³

et al. 2023

High‐Throughput Mass Spectrometry in Drug Discovery

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Field Dependence of Mobilities for Gas-Phase-Protonated Monomers and Proton-Bound Dimers of Ketones by Planar Field Asymmetric Waveform Ion Mobility Spectrometer (PFAIMS)

Cited by 121 publications

References 16 publications

Feasibility of Higher-Order Differential Ion Mobility Separations Using New Asymmetric Waveforms

Feasibility of Higher-Order Differential Ion Mobility Separations Using New Asymmetric Waveforms

Optimum waveforms for differential ion mobility spectrometry (FAIMS)

Differential Mobility Spectrometry and Its Application to High‐Throughput Analysis

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