Optimization of peptide separations by differential ion mobility spectrometry

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Differential ion mobility spectrometry (DIMS) separates gas-phase ions based on differential mobility in electric fields.
• DIMS complements mass spectrometry (MS) by resolving isobaric and isomeric species.
• Carrier gas composition and electric field strength influence DIMS separation resolution.

Purpose of the Study:

• To investigate the trade-offs between dispersion field strength and helium content in the carrier gas for DIMS separations.
• To determine optimal DIMS conditions for resolving isobaric peptides.
• To evaluate the impact of these parameters on ion transmission and overall sensitivity.

Main Methods:

• Comparative analysis of DIMS separations using varying dispersion fields and nitrogen-helium carrier gas mixtures.
• Separation and analysis of a model mixture containing three isobaric peptides.
• Measurement of resolution and ion transmission under different DIMS operating conditions.

Main Results:

• Maximum separation resolution for isobaric peptides was achieved using a high dispersion field (~72 kV/cm) with pure nitrogen carrier gas.
• Increased helium content in the carrier gas improved separation at constant dispersion fields but reduced the maximum accessible field strength.
• Conditions yielding maximum resolution resulted in the lowest ion transmission, indicating a significant sensitivity reduction.

Conclusions:

• Optimizing DIMS for maximum resolution requires a high dispersion field, favoring pure nitrogen carrier gas.
• A critical trade-off exists between achieving high resolution and maintaining high ion sensitivity in DIMS.
• Application-specific DIMS method development must carefully balance resolution and sensitivity requirements.