Commercial Precoated Layers for Enantiomer Separations and Analysis
Enantiomers have been separated on conventional layers, such as silica gel and reversed phase chemically bonded silica gel, by using diastereomeric derivatives produced by reaction with an optically pure reagent. Enantiomers are separated without prior synthetic formation of diastereomeric adducts by development in chiral systems having adequate enantioselectivity. In situ quantification of enantiomers can be carried out by densitometry in visible absorption, ultraviolet absorption, or fluorescence modes. Silica gel is by far the most frequently used layer material for thin layer chromatography (TLC), and its usual mode of separation without modification is normal phase adsorption. Commercial layers are available for separation of enantiomers by the mechanism of chiral ligand exchange under the name Chiralplate. Amino acid derivatives have been separated on Chiralplates using the mobile phases methanol/water/acetonitrile. Direct separations of enantiomers have been made using a variety of commercial achiral precoated TLC and high-performance TLC plates developed with a chiral mobile phase.