loading page

Determination of collisional cross section using microscale high-field asymmetric waveform ion mobility spectroscopy-mass spectrometry (FAIMS-MS).
  • Kristina Krasnova,
  • Colin Creaser,
  • James Reynolds
Kristina Krasnova
Loughborough University School of Science
Author Profile
Colin Creaser
Loughborough University School of Science
Author Profile
James Reynolds
Loughborough University School of Science

Corresponding Author:j.c.reynolds@lboro.ac.uk

Author Profile

Abstract

RATIONALE: Collisional cross sections (CCS) are an important characteristic of gas-phase ions that are measured using ion mobility-mass spectrometry (IMS). Typically, CCS measurements are performed with drift-tube IMS or travelling-wave IMS. However. in a high-field asymmetric waveform ion mobility (FAIMS) device, the non-linear path through the device makes CCS determination more challenging. This research explores whether CCS can be predicted using a microscale FAIMS by using known CCS standards. METHODS: An Owlstone ultraFAIMS microscale FAIMS spectrometer was coupled to an Orbitrap Exactive mass spectrometer. 2 different CCS standard mixtures (tetraalkylammonium halides and poly-DL-alanine oligomers) were used to evaluate the systems potential to predict CCS. Test peptides bradykinin acetate and substance P were used to determine prediction accuracy for singly and doubly charged peptide species using external calibration with a series of poly-DL-alanine peptides for +1, +2 charge states. RESULTS: Calibrations with excellent correlation coefficients (R 2 = 0.99) for both TAAHs and poly-DL-alanine were obtained. Good predictive accuracy was achieved for bradykinin [M+2H] 2+ with a ±0.5% difference between experimental and published CCS at a dispersion field strength (DF) of 250 Td, the model proved less accurate for bradykinin [M+H] + (±1.4% at 240 Td). The prediction accuracy for the [M+H] + and [M+2H] 2+ ions of substance P was within ±5% and ±3% at 250 Td respectively, while at higher DF values accuracy decreased to approximately 5%. CONCLUSIONS: Distinct relationships were observed between CCS and transmission CF with both calibrants. Optimum predictive performance was obtained at DF strengths of 240-260 Td. At lower DF accuracy is reduced by insufficient resolution of analyte ions from solvent cluster adducts while at higher DF values, poor transmission becomes a factor. Nevertheless, these data suggest microscale FAIMS can conduct CCS measurements with reasonable accuracy when the compound being measured has similar structural features to the CCS standards used.
22 Nov 2024Submitted to Rapid Communications in Mass Spectrometry
23 Nov 2024Submission Checks Completed
23 Nov 2024Assigned to Editor
23 Nov 2024Review(s) Completed, Editorial Evaluation Pending
03 Dec 2024Reviewer(s) Assigned