Size effect on fragmentation in tandem mass spectrometry

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Physical Chemistry

Background:

• Determining optimal fragmentation conditions is crucial for structural characterization in tandem mass spectrometry (MS/MS).
• Previous studies have explored factors influencing fragmentation efficiency, but a universal correlation for diverse molecules remained elusive.

Purpose of the Study:

• To systematically determine the characteristic collision energy/voltage (CCE/CCV) for 50% fragmentation across various molecule types and mass ranges.
• To establish a predictive correlation between CCE/CCV and precursor ion properties for simplified instrument tuning.

Main Methods:

• Systematic determination of CCE/CCV for poly(ethylene glycols) (PEG), poly(tetrahydrofuran) (PTHF), and peptides.
• Analysis of fragmentation data across different instrument types and experimental conditions.
• Statistical analysis to identify linear correlations between CCE/CCV and ion properties (mass, mass-to-charge ratio).

Main Results:

• A strong linear correlation (R(2) > 0.996) was observed between CCE and precursor ion mass for lithium-cationized PEGs up to 4.5 kDa.
• Similar linear correlations were found between CCV and mass-to-charge ratio for various polymers (R(2) = 0.991).
• These correlations hold across different instruments and experimental conditions, suggesting constant energy and entropy of activation within polymer classes.

Conclusions:

• The findings suggest rapid energy randomization in ions up to 4.5 kDa, validating the applicability of statistical rate theories.
• A simple proportional relationship exists between optimal excitation voltage and analyte mass for structurally similar compounds.
• This provides a practical method for high-throughput structural characterization via tandem MS by enabling straightforward instrument tuning.