Enhancing Performance of Liquid Sample Desorption Electrospray Ionization Mass Spectrometry Using Trap and Capillary...

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Biochemistry

Background:

• Desorption electrospray ionization mass spectrometry (DESI-MS) is a key technique for analyzing solid and liquid samples.
• Traditional liquid sample DESI-MS uses silica capillaries for sample transfer, limiting sensitivity and sample preparation options.

Purpose of the Study:

• To enhance liquid sample DESI-MS performance for trace analysis.
• To develop a more versatile platform for bioanalysis, including protein digestion and detection.

Main Methods:

• Replaced the standard silica capillary with a trap column containing chromatographic stationary phases (C4, C18).
• Modified the sample transfer capillary by covalently immobilizing enzymes for protein digestion.
• Utilized the modified system for direct analysis and online digestion of proteins and peptides.

Main Results:

• The trap column enabled trace analysis (nM concentrations) of organics and biomolecules in high salt matrices.
• Enzyme-modified capillaries achieved rapid (< 6 min) in-line digestion of proteins, including phosphoproteins.
• DESI-MS with the modified capillary demonstrated high sensitivity due to optimized solvent selection.

Conclusions:

• The improved liquid sample DESI-MS system significantly expands utility in bioanalysis.
• The trap column and enzyme-modified capillary approaches offer enhanced capabilities for sensitive detection and sample preparation.