Peak parking-moment analysis method for the measurement of surface diffusion coefficients

Area of Science:

• Analytical Chemistry
• Chromatography

Background:

• Surface diffusion is critical for understanding mass transfer kinetics in chromatography.
• Accurate measurement of surface diffusion coefficients (D(s)) is essential for optimizing chromatographic separations.
• Existing methods for D(s) measurement can be complex or time-consuming.

Purpose of the Study:

• To introduce and validate the peak parking-moment analysis (PP-MA) method for measuring surface diffusion coefficients (D(s)).
• To compare the PP-MA method with the established pulse response-moment analysis (PR-MA) method.
• To investigate the mechanism of surface diffusion and its relationship with retention and solvent properties.

Main Methods:

• Application of the peak parking-moment analysis (PP-MA) method.
• Measurement of surface diffusion coefficients (D(s)) in reversed-phase liquid chromatography (C(18)-silica gel, 70% methanol/water).
• Comparison with pulse response-moment analysis (PR-MA) data.

Main Results:

• The PP-MA method yielded D(s) values consistent with those obtained by the PR-MA method.
• The PP-MA method was demonstrated as a viable alternative for D(s) measurement.
• A correlation was found between retention strength, solvent structure, and surface diffusion.

Conclusions:

• The peak parking-moment analysis (PP-MA) method is a validated and effective technique for measuring surface diffusion coefficients.
• Surface diffusion is influenced by molecular retention strength and solvent-induced structural changes on the stationary phase surface.
• The PP-MA method provides valuable insights into mass transfer kinetics in chromatographic systems.