Characterization of a High Field FAIMS System

摘要

A combination of computational fluid dynamic modeling, ion trajectory simulation and experimental hardware was used in this study. A second FAIMS gas inlet positioned opposite of the ion inlet does not change the flow rate of desolvation gas emanating from the entrance plate but does change the flow profile (more uniform). A FAIMS electrode set with a single gas inlet creates a non-focused gas profile at the ion inlet causing ion loss on the outside of the outer electrode. Once inside the FAIMS cell, the single gas inlet electrode preferentially focuses the gas flow under the center electrode with very little of the flow going over the center electrode. A FAIMS electrode set with dual gas inlets creates a focused gas flow into the ion inlet with little loss to the outside of the outer electrode. Inside the FAIMS cell, the dual gas inlet electrode allows for gas flow both above and below the center electrode. FAIMS gas flow optimizes at slightly higher flow rates for the dual gas inlet electrodes, likely due to changes in the desolvation gas flow profile emanating from the entrance plate. Gains in ion signal are limited (and mass-to-charge dependent) due to increased ion loss at the inner electrode with the dual gas inlet electrodes.