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

Abstract

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 ...

Using a nanoelectrospray-differential mobility spectrometer-mass spectrometer system for the analysis of oligosaccharides with solvent selected control over ESI aggregate ion formation

“…ϩ would be detected not only at its original transmission CV of 2.9 V but also at CVs where ions associated with their fragmentation product [MNH 4 ] ϩ are transmitted through FAIMS. Low-energy conditions at the mass spectrometer interface help to differentiate ions formed in ESI from their dissociation products" [22]. In our study, we also observed oligosaccharide aggregate ion formation and dissociation at the MS interface.…”

“…Gabryelski et al investigated the use of ESI-FAIMS-MS for oligosaccharide separation, and explored the addition of various salts to the sample solvent solutions for their effects on ionization and FAIMS selectivity [22]. ϩ would be detected not only at its original transmission CV of 2.9 V but also at CVs where ions associated with their fragmentation product [MNH 4 ] ϩ are transmitted through FAIMS.…”

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

“…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.…”

“…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.…”

Analysis of Triazines and Associated Metabolites with Electrospray Ionization Field-Asymmetric Ion Mobility Spectrometry/Mass Spectrometry

“…26 Coupling of atmosphericpressure ionization techniques (ESI, APCI) via FAIMS to MS was explored starting in the late 1990's by Guevremont and colleagues, 27,28 who also showed that the cylindrical FAIMS has an ion focusing effect due to electrical field gradients. 29 ESI-FAIMS-MS has been employed advantageously in proteomics applications, 30 analysis of polysaccharides, 31,32 and drug discovery activities. 33 It should be noted that FAIMS separates ions on a timescale which is compatible with those of both liquid chromatography and tandem MS. 33,34 This paper describes the results of a pilot study designed to assess the utility of FAIMS in the analysis of triazines and associated metabolites.…”