Field-Switching Repeller Flowing Atmospheric-Pressure Afterglow Drift Tube Ion Mobility Spectrometry

Area of Science:

• Analytical Chemistry
• Spectrometry
• Ion Mobility Spectrometry

Background:

• Drift tube ion mobility spectrometry (DTIMS) is a powerful analytical technique.
• Traditional Bradbury-Nielsen gates (BNGs) in DTIMS can suffer from gate depletion effects (GDE).
• Flowing atmospheric pressure afterglow (FAPA) sources offer advantages for ionization in DTIMS.

Purpose of the Study:

• To develop and evaluate a field-switching (FS) technique for DTIMS using a FAPA source.
• To replace the BNG with a tip-repeller electrode to mitigate GDE.
• To optimize DTIMS parameters for improved peak shape and reduced neutral-ion reactions.

Main Methods:

• Implementation of a field-switching (FS) technique with a FAPA source in DTIMS.
• Utilized a tip-repeller electrode instead of a BNG to avoid GDE.
• Optimized DTIMS inlet aperture, FAPA, and repeller operating conditions (gas flow rates, voltages, etc.).
• Captured ion mobility spectra and calculated reduced mobility values.

Main Results:

• Optimized DTIMS parameters led to improved peak shape and width.
• Successfully replaced BNG with a tip-repeller electrode, reducing GDE.
• Achieved a 6-fold improvement in the limit of detection (LOD) for 2,6-DTBP and acetaminophen.
• Demonstrated enhanced performance of the FS-FAPA-DTIMS compared to BNG-based systems.

Conclusions:

• The developed field-switching technique with FAPA-DTIMS offers enhanced analytical performance.
• Replacing BNG with a tip-repeller electrode effectively overcomes GDE limitations.
• The optimized FS-FAPA-DTIMS system provides significantly improved sensitivity and detection limits.