Comparative Enantiomer-Resolving Ability of Coated and Covalently Immobilized Versions of Two Polysaccharide-Based Chiral Selectors in High-Performance Liquid Chromatography

The separation of enantiomers of over 175 randomly selected chiral acidic, basic, and neutral compounds was studied on 4 polysaccharide-based chiral columns made by coating or covalent attachment of cellulose 3,5-dichlorophenylcarbamate or amylose 3,5-dimethylphenylcarbamate on the surface of silica. Triscarbamate derivatives of cellulose or amylose were used for the preparation of coated-type columns, while in the case of covalently immobilized chiral stationary phases, the respective polysaccharides were not completely carbamoylated but only close to triscarbamates. It was found that this minimal difference in the chemical composition of the polysaccharide derivatives resulted in significantly different enantiomer-resolving ability for certain groups of chiral compounds while only marginally different for other chiral analytes. This potential difference between coated- and covalently immobilized versions of the "same" chiral selector must be considered in method development with these columns, as well as in method transfer between them.