Optimization of Peptide Analysis Using High-Field Asymmetric Waveform Ion Mobility Spectrometry (2012)

Undergraduates: Kyle Stevens, none Samantha Isenberg none

Faculty Advisor: Gary Glish
Department: Chemistry

---

High-field asymmetric waveform ion mobility spectrometry (FAIMS), coupled with mass spectrometry, separates gas-phased ions based on their distinct differential mobilities between high and low electric field strengths. Voltages are applied to parallel electrodes to produce alternating high and low electric fields. FAIMS acts as a filter selecting for a target analyte while other compounds in the sample are neutralized on the electrodes. With an ion transit time on the order of milliseconds, it is the speed of this method that makes FAIMS ideal for the analysis of complex biological samples in acute environments where speed is essential. To ensure the most accurate and sensitive results various parameters must first be optimized. In this project we investigated how the physical dimensions of the FAIMS electrodes affected the ion losses observed during the separation as the electric field strengths were varied. Ion losses for peptides were determined as a function of electric field strength. The electrodes were changed between 25 mm and 50 mm in length; as well as 0.3 mm, 0.5 mm, and 1.0 mm gaps between the two electrodes. It was noted that for all combinations of electrode length and gap, as the electric field strength was increased, an increase in ion losses was witnessed. It was also determined that the longer 50 mm electrodes allowed for higher ion losses than the shorter electrodes, and the narrower gaps allowed for greater ion losses than the wider gaps.