Chiral Mobile Phase Additives
Chiral mobile phase additives (CMPAs) are generally used to perform direct chiral separation in thin-layer chromatography. This mode offers the advantages of flexibility and low cost as compared to the equivalent chiral stationary phase. In the CMPAs method, enantiomeric separation is accomplished by the formation of a pair of transient diastereomeric complexes between a racemic analyte and the CMPA. Derivatization of the structure of cyclodextrins (CD) atthehydroxyl groups represents an alternative route to improve their hydrosolubility and enhance enantioselectivity. The degree of substitution in derivatized CDs may affect the chiral separation mechanism. Macrocyclic glycopeptides/antibiotics are a relatively new class of chiral selectors with favorable chromatographic properties. Proteins are composed of chiral monomers, organized in different sequences, providing a huge structural diversity. The inherent chirality of the amino acid residues induces chiral recognition of the protein.