Exploring adsorption-desorption kinetics and eddy dispersion in enantioselective hydrophilic interaction...

This research examined the kinetic behavior of two chiral probes (FMOC-Alanine and Haloxyfop) using a zwitterionic teicoplanin-based column and an aqueous-methanol mobile phase. More specifically, experimental results, supported by literature data measured using the same elution mode, indicate that the presence of a water layer adsorbed on the particle surface hinders analyte surface diffusion leading to localized adsorption. This shows cascading effects on longitudinal diffusion, solid-liquid mass transfer resistance and eddy dispersion, which become analyte-independent. The only difference in the measured plate heights is therefore given only by slow adsorption-desorption kinetics, confirming an important correlation between analyte structure and the extent of band broadening in chiral chromatography. The findings reported in this study can be expanded to other molecules, suggesting that similar kinetic behavior could be expected if the same experimental conditions are maintained (e.g., same column manufacturer, silica particles, and elution mode). This would help accelerating the method development and the understanding of both the chiral recognition mechanism and the sources of band broadening occurring in chiral chromatography.