A new method of separation of multi-atomic ions by mobility at atmospheric pressure using a high-frequency amplitude-asymmetric strong electric field

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A challenging aspect of structural elucidation of carbohydrates is gaining unambiguous information for anomers, linkage, and position isomers. Such isomers with identical mass can't be easily distinguished in mass spectrometry and a separation step is required prior to mass spectrometry identification. In our laboratory, gas-phase separation and differentiation of anomers, linkage, and position isomers of disaccharides was achieved using High-Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS). The FAIMS method responds to changes in ion mobility at high field rather than absolute values of ion mobility, and was shown to provide efficient separation and identification of disaccharide isomers at high sensitivity. Separation of analyzed disaccharide isomers can be accomplished at low nM level in a matter of seconds without sample purification or fractionation. Capability for examining a large population of ionic species of disaccharides by this method allowed for correlating structural details of disaccharide isomers with their separation properties in FAIMS. Results for disaccharide isomers indicate that this method could be applied to a larger group of carbohydrates. ( Mass spectrometry has shown a unique ability to resolve certain structural ambiguities. Permethylation is a well developed but time-consuming GC-MS method in linkage analysis of oligosaccharides [1,2]. Other methods implementing the derivatization of saccharides have been used to obtain their structural information [3][4][5][6][7][8][9][10][11]. The soft mass spectrometry ionization techniques such as fast atom bombardment (FAB) [12][13][14][15][16], liquid secondary ionization mass spectrometry (LSIMS) [17,18], along with matrix-assisted laser desorption ionization (MALDI) [19 -23], and electrospray ionization (ESI) [24 -28] have gained attention as approaches to investigate underivatized oligosaccharides. Collision-induced dissociation (CID) offers the possibility to assign details of carbohydrate structure such as sugar sequence for linear oligosaccharides [12], linkage position [12,[15][16][17]29], and differentiation of anomers [25,30]. In addition to analyzing protonated or deprotonated molecular ions of saccharides in CID, alkali metal adduct ions have been used to promote fragmentation of ligand-carbohydrate complexes. In the positive ion mode, calcium and magnesium adducts of oligosaccharides were investigated for the elucidation of the linkage position of trisaccharides [26] and cobalt complexes have been used to differentiate the anomeric configuration of disaccharides [30]. In the negative ion mode, decomposition of chloride adducts was investigated for differentiation of the linkage position of disaccharides [31].Despite recent advances in tandem mass spectrometry of carbohydrates, the spectral differences for some isomers are very small and they do not provide unambiguous identification. This is especially true when a mixture of isomers with the same m/z has to be analyzed. In such applications a separation step is required ...

Section: Ion Separation In Faimsmentioning

confidence: 99%

Rapid and sensitive differentiation of anomers, linkage, and position isomers of disaccharides using High-Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS)

Gabryelski

Froese

2003

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“…However, the disadvantage is negligible when the perturbation period is much shorter than the residence time in FAIMS, and ripple adjustment appears to offer a practical method for modifying FAIMS resolution. S eparation of ions in the gas-phase using field asymmetric waveform ion mobility spectrometry (FAIMS) extends back two decades [1][2][3][4][5][6][7]. However, FAIMS was not widely used until its coupling to electrospray ionization mass spectrometry [8,9], which has expanded its utility to environmental [10 -13] and biological [14 -18] applications, in addition to traditional detection of airborne volatiles [19 -23].…”

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confidence: 99%

FAIMS operation for realistic gas flow profile and asymmetric waveforms including electronic noise and ripple

Shvartsburg

Tang

Smith

2005

The use of field asymmetric waveform ion mobility spectrometry (FAIMS) has rapidly grown with the advent of commercial FAIMS systems coupled to mass spectrometry. However, many fundamental aspects of FAIMS remain obscure, hindering its technological improvement and expansion of analytical utility. Recently, we developed a comprehensive numerical simulation approach to FAIMS that can handle any device geometry and operating conditions. The formalism was originally set up in one dimension for a uniform gas flow and limited to ideal asymmetric voltage waveforms. Here we extend the model to account for a realistic gas flow velocity distribution in the analytical gap, axial ion diffusion, and waveform imperfections (e.g., noise and ripple). The nonuniformity of the gas flow velocity profile has only a minor effect, slightly improving resolution. Waveform perturbations are significant even at very low levels, in some cases ϳ0.01% of the nominal voltage. These perturbations always improve resolution and decrease sensitivity, a trade-off controllable by variation of noise or ripple amplitude. This trade-off is physically inferior to that obtained by adjusting the gap width and/or asymmetric waveform frequency. However, the disadvantage is negligible when the perturbation period is much shorter than the residence time in FAIMS, and ripple adjustment appears to offer a practical method for modifying FAIMS resolution. S eparation of ions in the gas-phase using field asymmetric waveform ion mobility spectrometry (FAIMS) extends back two decades [1][2][3][4][5][6][7]. However, FAIMS was not widely used until its coupling to electrospray ionization mass spectrometry [8,9], which has expanded its utility to environmental [10 -13] and biological [14 -18] applications, in addition to traditional detection of airborne volatiles [19 -23]. The recent advent of commercial FAIMS systems (Ionalytics Selectra [17,24] and Sionex DMS [23,25]) is increasing the acceptance of FAIMS and diversifying its applications.While FAIMS analyses have become increasingly common, the fundamentals remain relatively poorly understood [18]. Phenomenologically, ions are separated by the difference between mobilities at high and low electric fields (E) (respectively K H and K L ) that in general differ as ion mobilities in gases depend on the field. Thus, FAIMS measures the mean derivative of mobility with respect to field ͗ѨK⁄ѨE͘ (over a certain range of E), in contrast to the conventional ion mobility spectrometry [26,27] that determines absolute mobilities (K). The K(E) function can be expressed as a polynomial over even powers of E/N, where N is the buffer gas number density [28,29]:Mobilities tend to significantly deviate from zero-field values K(0) at E/N Ն ϳ30 to 40 Td, which defines the lower limit for electric fields useful in FAIMS operation. The upper limit is given by the onset of electrical breakdown in gas, which depends on the gas identity and number density, and (to a lesser extent) the width and geometry of the gap between electrodes (the...

“…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]: …”

Section: -43]mentioning

confidence: 99%

“…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]: …”

mentioning

confidence: 99%

“…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].…”

mentioning

confidence: 99%

See 1 more Smart Citation

Optimum waveforms for differential ion mobility spectrometry (FAIMS)

Shvartsburg

Smith

2008

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]: