title: Analysis of Supramolecular Complexes of 3-Methylxanthine with Field Asymmetric Waveform Ion Mobility Spectrometry Combined with Mass Spectrometry.
abstract: Miniaturised field asymmetric waveform ion mobility spectrometry (FAIMS), combined with mass spectrometry (MS), has been applied to the study of self-assembling, noncovalent supramolecular complexes of 3-methylxanthine (3-MX) in the gas phase. 3-MX forms stable tetrameric complexes around an alkali metal (Na(+), K(+)) or ammonium cation, to generate a diverse array of complexes with single and multiple charge states. Complexes of (3-MX)n observed include: singly charged complexes where n = 1-8 and 12 and doubly charged complexes where n = 12-24. The most intense ions are those associated with multiples of tetrameric units, where n = 4, 8, 12, 16, 20, 24. The effect of dispersion field on the ion intensities of the self-assembled complexes indicates some fragmentation of higher order complexes within the FAIMS electrodes (in-FAIMS dissociation), as well as in-source collision induced dissociation within the mass spectrometer. FAIMS-MS enables charge state separation of supramolecular complexes of 3-MX and is shown to be capable of separating species with overlapping mass-to-charge ratios. FAIMS selected transmission also results in an improvement in signal-to-noise ratio for low intensity complexes and enables the visualization of species undetectable without FAIMS.
authors.affiliation: Center for Analytical Science, Department of Chemistry, Loughborough University, Loughborough, LE11 3TU, UK.
authors.forename: Kayleigh L
authors.initials: KL
authors.lastname: Arthur
authors.affiliation: Center for Analytical Science, Department of Chemistry, Loughborough University, Loughborough, LE11 3TU, UK.|Department of Chemistry and Biochemistry, New Mexico State University, MSC 3C, P.O. Box 3001, Las Cruces, NM, 88003-8001, USA.
authors.forename: Gary A
authors.initials: GA
authors.lastname: Eiceman
authors.affiliation: Center for Analytical Science, Department of Chemistry, Loughborough University, Loughborough, LE11 3TU, UK. J.C.Reynolds@lboro.ac.uk.
authors.forename: James C
authors.initials: JC
authors.lastname: Reynolds
authors.affiliation: Center for Analytical Science, Department of Chemistry, Loughborough University, Loughborough, LE11 3TU, UK. C.S.Creaser@lboro.ac.uk.
authors.forename: Colin S
authors.initials: CS
authors.lastname: Creaser
keywords: Charge state separation; Dissociation; FAIMS; Field asymmetric waveform ion mobility spectrometry; In-source CID; Mass spectrometry; Self-assembling complexes