Tuneable peak deformations in chiral liquid chromatography

Area of Science:

• Chiral Chromatography
• Separation Science
• Analytical Chemistry

Background:

• Chiral stationary phases (CSPs) combined with polar additives in eluents can cause significant enantiomer band deformations.
• These deformations impact both analytical and preparative chromatographic separations, affecting resolution and loading capacity.

Purpose of the Study:

• To provide a theoretical background for understanding enantiomer band deformations in chiral chromatography.
• To experimentally verify the theoretical model using beta-blocker enantiomer separation on a teicoplanin stationary phase.
• To demonstrate the ability to control peak shapes by adjusting eluent composition.

Main Methods:

• Theoretical modeling of enantiomer band deformations.
• Experimental separation of beta-blocker enantiomers using a teicoplanin stationary phase (Chirobiotic T) with triethylamine/acetic acid eluents.
• Determination of adsorption isotherm parameters using an inverse method.
• Computer simulations to validate the theoretical model and observed deformations.

Main Results:

• Peak shapes of eluted enantiomers can be tuned by varying the organic solvent composition in the eluent.
• An advantageous separation occurs when the first enantiomer exhibits an anti-Langmuirian shape and the second shows a normal Langmuirian shape.
• This opposing peak tailing allows for baseline resolution at higher sample loads compared to cases with same-direction tailing.

Conclusions:

• The study successfully explains the origin of enantiomer band deformations through theoretical and experimental approaches.
• Optimizing eluent composition is crucial for controlling peak shapes and enhancing chiral separation efficiency.
• The findings enable higher loading capacities in preparative chiral separations by manipulating adsorption isotherms.