Investigating ion transmission in differential ion mobility spectrometry (2013)

Undergraduates: Kyle Stevens, Samantha Isenberg

Faculty Advisor: Gary Glish
Department: Chemistry

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Differential ion mobility spectrometry (DIMS) separates gas-phase ions based on their distinct differences in ion mobilities at high versus low electric fields. Voltages are applied to parallel electrodes to produce alternating high and low electric fields. DIMS can act as a filter, selecting for a target analyte while other compounds in the sample are neutralized on the electrodes. DIMS is easily coupled to mass spectrometry (MS) and ion transit time through the device is on the order of milliseconds, making DIMS amenable to applications requiring fast separation prior to analysis by mass spectrometry. To ensure the most sensitive results, while maintaining adequate resolution, various parameters must first be optimized. In this project we investigated how the physical dimensions of the DIMS electrodes and carrier gas parameters affected the ion transmission observed during the separation as the electric field strength was varied. Ion transmission was studied using various peptides and an ammonium salt. Additionally, we investigated an extra peak of unknown origin for some peptide analytes. By altering electrospray ionization conditions and settings in the ion transfer optics of the mass spectrometer, we are able to confirm the peak was a result of charge reduction in the ion transfer optics.