Improvements for High Resolution Analysis on a Modified Tribrid Mass Spectrometer

Significance of the Topic

The performance of Fourier Transform Mass Spectrometry (FTMS), especially high–resolution Orbitrap instruments, is constrained by ion trajectory instabilities, gas collisions, and electrode imperfections. Addressing these limitations is critical to enhance resolution, minimize peak coalescence, and improve signal‐to‐noise ratios in proteomics, lipidomics, and metabolomics applications.

Objectives and Study Overview

This work presents targeted modifications to a Thermo Scientific Orbitrap Fusion Tribrid mass spectrometer. Two main changes were implemented: refining the vacuum conductance path to reduce neutral gas intrusion and optimizing the matching of Orbitrap electrodes. The study evaluates the impact of these alterations on transient decay, resolution, peak coalescence, and real‐world analytical examples.

Methodology and Instrumentation

The instrument was retrofitted with enhanced pumping (from 80 L/s to 290 L/s) and improved gas conductance at the C‐trap exit. Electrode profiles were carefully tuned to approach the ideal field distribution. Performance was assessed via:

• IRM leak‐rate tests using standard calibration mixtures (n-butylamine, caffeine, MRFA peptide, Ultramark).
• Transient decay and signal‐to‐noise measurements for myoglobin and carbonic anhydrase II at varied pressures.
• Peak coalescence assays on peptide MRFA by monitoring the onset S/N for closely spaced isotopologues.
• Lipid separation of phosphatidylcholine isomers at 500k resolving power.
• Metabolomic profiling of lansoprazole and its glucuronide in human urine by LC–MS.

Key Results and Discussion

Modifications yielded a 30–50 % faster transient decay, boosting S/N at higher pressures. Coalescence tests showed a 36 % gain in the ability to resolve 11 mDa‐spaced peaks. Lipidomics experiments at 500k resolving power separated PC (16:0,18:1) from its isotope overlap. Metabolomics data successfully distinguished lansoprazole, its 18O isotopologue, and glucuronide metabolite with sub–3 mDa differences.

Benefits and Practical Applications

• Enhanced isotopic resolution for intact proteins in top‐down proteomics.
• Reduced ion packet decay, increasing data reliability in high‐throughput workflows.
• Improved separation of low‐abundance analytes from isobaric interferences in lipidomics and metabolomics.
• Adaptability of modifications to existing Orbitrap platforms without major redesign.

Future Trends and Applications

Further innovations may include active control of residual gas composition, dynamic electrode tuning, and integration with ultrahigh‐pressure front ends. Such advances will push FTMS toward resolutions above 1 000 000 while preserving ion coherence, enabling more detailed characterization of complex biomolecules.

Conclusion

By reinforcing vacuum performance and precisely aligning electrode fields, the modified Orbitrap Fusion instrument achieves significantly improved transient fidelity, higher S/N, and reduced peak coalescence. These gains translate into practical enhancements for proteomic, lipidomic, and metabolomic analyses across academic and industrial settings.

References

1. A. Makarov and E. Denisov, J. Am. Soc. Mass Spectrom. 20 (2009) 1486–1495.
2. D.W. Mitchell and R.D. Smith, Phys. Rev. A 52 (1995) 4366; A. Kharchenko et al., J. Am. Soc. Mass Spectrom. 23 (2012) 977–987.
3. A. Makarov et al., “Crowd Control of ions in Orbitrap mass spectrometry,” ASMS 2012.