Mass transfer mechanism in chiral reversed phase liquid chromatography

• The five contributions to the mass transfer mechanism in chiral chromatography were measured.
• These contributions include the short-range and the long-range eddy dispersion terms.
• They also include the longitudinal diffusion and solid–liquid mass transfer resistance term.
• A protocol permitting their accurate measurements was designed and followed.
• The work was done with the stilbene enantiomers eluted on a Cellulose-1 column.

The mechanism of mass transfer in chiral chromatography was investigated using an experimental protocol already applied in RPLC and HILIC chromatography. The different contributions to the reduced height equivalent to a theoretical plate (HETP) include the longitudinal diffusion HETP term, the solid–liquid mass transfer resistance HETP term, the short-range eddy dispersion HETP term, and the long-range eddy dispersion HETP term. Their accurate measurement permits the determination of the adsorption rate constant kads of trans-stilbene enantiomers on a column packed with Lux 5 μm Cellulose-1 particles. The experimental results demonstrate that the number of adsorption–desorption steps per unit time of chiral compounds on polysaccharide-based chiral stationary phases is four orders of magnitude smaller than that of achiral compounds.