High-Resolution Ion Mobility as an Alternative to Quadrupole-Based Precursor Isolation for Reducing Chimeric...

Area of Science:

• Proteomics
• Analytical Chemistry
• Mass Spectrometry

Background:

• Traditional quadrupole isolation in mass spectrometry often leads to chimeric spectra, complicating fragmentation analysis.
• Isobaric and isomeric peptides present challenges for selective precursor isolation using conventional methods.

Purpose of the Study:

• To evaluate high resolution ion mobility (HRIM) as an alternative precursor isolation technique for mass spectrometry.
• To compare the rate of chimeric spectrum generation between HRIM and quadrupole-based isolation.
• To assess the potential of HRIM for resolving isobaric and isomeric peptides.

Main Methods:

• Meta-analysis of predicted tryptic peptide features from the human proteome.
• Experimental validation using a HRIM-QTOF mass spectrometry system.
• Comparison of chimeric spectrum rates with varying HRIM peak capacities and quadrupole isolation windows.

Main Results:

• HRIM separation (peak capacity 100) yielded chimeric spectra at a rate comparable to a ~5 Th quadrupole isolation window.
• HRIM enabled the generation of non-chimeric spectra for isobaric and isomeric peptides, which are unresolvable by quadrupole filters.
• Combining HRIM and MS isolation increased precursor isolation specificity by over 10-fold compared to either technique alone.

Conclusions:

• High resolution ion mobility is a viable and advantageous alternative for precursor isolation in mass spectrometry-based proteomics.
• HRIM significantly enhances precursor isolation specificity, particularly for complex proteomic samples containing isobaric and isomeric interferences.
• The integration of HRIM with mass spectrometry offers a substantial improvement in data quality and analytical depth for proteomic studies.