High-Resolution Field Asymmetric Waveform Ion Mobility Spectrometry Using New Planar Geometry Analyzers

Shvartsburg, Alexandre A.; Smith, Richard D.

doi:10.1021/ac052020v

Cited by 171 publications

(320 citation statements)

References 77 publications

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“…Consequently, by fixing the CV value, a subset of ions is allowed to pass through the FAIMS, whereas other ions are lost to the walls of the device. FAIMS is readily coupled between an atmospheric pressure ionization source and a mass spectrometer [12][13][14][15][16] and, because of its unique ion-separation mechanism [17], FAIMS offers additional selectivity for bioanalytical applications. Indeed, FAIMS has been previously interfaced to atmospheric pressure ionization sources such as ESI [12] and APCI [8] operating at low liquid flow rates (and thus low temperatures) and has been found to significantly lower detection limits by reducing background ion current without sacrificing absolute signal intensity [18 -20].…”

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confidence: 99%

Characterization of a temperature-Controlled FAIMS system

Barnett

Belford

Dunyach

et al. 2007

J. Am. Soc. Mass Spectrom.

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High-field asymmetric waveform ion mobility spectrometry (FAIMS) focuses and separates gas-phase analyte ions from chemical background, offering substantial improvements in the detection of targeted species in biological matrices. Ion separations have been typically performed at atmospheric pressure and ambient temperature, although routine small molecule quantitation by LC-MS (and thus LC-FAIMS-MS) is generally performed at liquid flow rates (e.g., in excess of 200 L/min) in which atmospheric pressure ionization sources (e.g., APCI and ESI) need to be run at elevated temperatures to enhance ion desolvation. Heat from the ionization source and/or the mass spectrometer capillary interface is shown to have a significant impact on the performance of a conventional FAIMS electrode set. This study introduces a new FAIMS system that uses gas heating/cooling to quickly reach temperature equilibrium independent of the external temperature conditions. A series of equations and balance plots, which look at the effect of temperature and other variables, on the normalized field strength (E/N), are introduced and used to explain experimental observations. Examples where the ion behavior deviates from the predicted behavior are presented and explanations based on clusters or changes in ion-neutral interactions are given. Consequences of the use of temperature control, and in particular advantages of using different temperature settings on the inner and outer electrodes, for the purpose of manipulating ion separation are described. ecause of its high sensitivity and selectivity, liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) has become the method of choice for quantitation of bioorganic compounds in biological matrices such as urine or blood plasma [1][2][3]. To preserve LC conditions and flow rates typically used with LC-UV (e.g., 1 mL/min), mass spectrometer manufacturers needed to adapt electrospray ionization (ESI) sources, which were initially operated at much lower liquid flow rates [4,5], to achieve sufficient ion desolvation. Consequently, sources that use the addition of heat to accelerate ion desolvation were created [6,7] and further developed into the commercial sources that are used today (e.g., Heated Electrospray; H-ESI™ and TurboIonSpray; TIS™). Despite the widespread utility offered by LC-MS/MS, because of the complexity of biological matrices, in many instances (e.g., high background [8], co-eluting interferences [9]) additional selectivity in an analysis is still required.High-field asymmetric waveform ion mobility spectrometry (FAIMS) is a gas-phase ion-separation technique that is based on compound-dependent differences in an ion's mobility at high field (K h ) relative to low field (K) [10,11]. With FAIMS, deviations in ion mobility resulting from the high electric fields are reflected experimentally by the compensation voltage (CV) of transmission for a particular analyte. Consequently, by fixing the CV value, a subset of ions is allowed to pass through the FAIMS, whereas other i...

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confidence: 99%

Characterization of a temperature-Controlled FAIMS system

Barnett

Belford

Dunyach

et al. 2007

J. Am. Soc. Mass Spectrom.

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“…Those were resolved by FAIMS as deprotonated anions in N 2 [59] and protonated cations in 1:1 He/N 2 , [4] in both cases just barely. For anions, the experimental E D /N was 67 Td, where a R equals Ϫ0.15 for (Leu Ϫ H) Ϫ and Ϫ0.05 for (Ile Ϫ H) Ϫ (Table 2).…”

Section: Targeted Separationsmentioning

confidence: 99%

“…While focusing improves ion transmission through FAIMS, it introduces discrimination based on a(E/N) and limits the resolving power R by rendering ions with multiple E C stable in the gap. For low ion currents, the disadvantages outweigh gains and the overall performance (quantified via the resolution/sensitivity diagrams) maximizes for planar gaps [4]. This study formally addresses planar FAIMS, but the conclusions should extend to all geometries.…”

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confidence: 98%

“…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].…”

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confidence: 99%

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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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“…The ROMIAC also demonstrates high resolution with the TAAX standards (close to R nd ; Table S4), though resolution of the calibrant peptides and proteins were generally not as high as those of the TAAX standards (Table S6). This reduced resolution for peptides is fairly typical and is often assigned to the existence of multiple conformers within the mobility envelope [12,13,14,15,16,17] Values from [6]. Mobility values are in units of [cm…”

Section: Calibrationsmentioning

confidence: 99%

Ion Mobility-Mass Spectrometry with a Radial Opposed Migration Ion and Aerosol Classifier (ROMIAC)

et al. 2013

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The first application of a novel differential mobility analyzer, the radial opposed migration ion and aerosol classifier (ROMIAC), is demonstrated. The ROMIAC uses antiparallel forces from an electric field and a cross-flow gas to both scan ion mobilities and continuously transmit target mobility ions with 100% duty cycle. In the ROMIAC, diffusive losses are minimized, and resolution of ions, with collisional cross-sections of 200–2000 Å2, is achieved near the nondispersive resolution of ∼20. Higher resolution is theoretically possible with greater cross-flow rates. The ROMIAC was coupled to a linear trap quadrupole mass spectrometer and used to classify electrosprayed C2–C12 tetra-alkyl ammonium ions, bradykinin, angiotensin I, angiotensin II, bovine ubiquitin, and two pairs of model peptide isomers. Instrument and mobility calibrations of the ROMIAC show that it exhibits linear responses to changes in electrode potential, making the ROMIAC suitable for mobility and cross-section measurements. The high resolution of the ROMIAC facilitates separation of isobaric isomeric peptides. Monitoring distinct dissociation pathways associated with peptide isomers fully resolves overlapping peaks in the ion mobility data. The ability of the ROMIAC to operate at atmospheric pressure and serve as a front-end analyzer to continuously transmit ions with a particular mobility facilitates extensive studies of target molecules using a variety of mass spectrometric methods.

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High-Resolution Field Asymmetric Waveform Ion Mobility Spectrometry Using New Planar Geometry Analyzers

Cited by 171 publications

References 77 publications

Characterization of a temperature-Controlled FAIMS system

Characterization of a temperature-Controlled FAIMS system

Optimum waveforms for differential ion mobility spectrometry (FAIMS)

Ion Mobility-Mass Spectrometry with a Radial Opposed Migration Ion and Aerosol Classifier (ROMIAC)

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