According to some theoretical models separation on these CSPs is based on a three-point attachment between the solute and the bonded chiral ligand on the surface of the stationary phase.
The naturally occurring polysaccharide form the basis for an important group of columns designed for chiral separation.
[20] Polysaccharide-based stationary phase have a high loading capacity, many chiral centers and complicated stereochemistry, and can be used for the separation of a wide range of compounds.
The electron-donating ether oxygens are positioned within the inner wall of the crown cavity, and are encircled by methylene groups in a collar-like arrangement.
[23] While chiral separation mechanisms are understandable in certain scenarios, and the retention characteristics of analytes within the chromatographic columns can occasionally be elucidated, the precise combination of chiral stationary phases (CSPs) and mobile-phase compositions that required to effectively resolve a specific enantiomeric pair often remains elusive.
The chemistry of CSP ligands significantly influences the creation of in-situ diastereomeric complexes upon the stationary phase surface.
However, other method's conditions, such as mobile-phase solvents, their composition, mobile phase additives and column temperature can play equally critical roles.
The final resolution of the enantiomers is the outcome of combination of intermolecular forces, and even a subtle change in them can determine the success or failure of separation.
This complexity prevents from establishing routine method-development protocols that are universally applicable to a diverse range of enantiomers.
That's why the standard approach in the method development is high throughput screening, to evaluate or examine a series of stationary phases, using various mobile-phase combinations, to increase the chance of finding a suitable separation condition.