Coupling Charge Reduction Mass Spectrometry to Liquid Chromatography for Complex Mixture Analysis.

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Separation Science

Background:

• Electrospray ionization (ESI) of complex mixtures often yields intricate mass spectra due to multiple analyte charging.
• Multiple charge states complicate data interpretation by causing isobaric interferences and spectral congestion.
• Existing charge reduction techniques are limited to direct infusion mass spectrometry (MS).

Purpose of the Study:

• To introduce and evaluate a novel liquid chromatography/electrospray ionization/charge reduction/mass spectrometry (LC/CR/MS) technique.
• To demonstrate the ability of LC/CR/MS to reduce analyte charge states prior to mass analysis.
• To showcase the utility of LC/CR/MS for analyzing complex mixtures and overcoming MS challenges.

Main Methods:

• Synthetic polyols and surfactants were separated using liquid chromatography (LC).
• Analyte ions were subjected to polonium-210 alpha-particle radiation for charge reduction.
• The charge-reduced ions were analyzed using mass spectrometry (MS).

Main Results:

• LC/CR/MS analysis of poly(ethylene glycol) (PEG5000) reduced the average charge state from 5.88+ to 1.00+.
• This reduction significantly decreased spectral complexity and simplified data interpretation.
• LC/CR/MS successfully characterized polyol composition, including initiator, monomer identity/amount, and molecular weight, in complex polyol mixtures.

Conclusions:

• LC/CR/MS is a novel analytical technique for analyzing complex mixtures.
• The method effectively reduces ion charge states, simplifying mass spectral analysis.
• LC/CR/MS offers significant advantages for analyzing challenging samples, such as polyols and surfactants.