Chiral Separation of Amino Acid Enantiomers
The success of a chiral separation depends upon the formation of diastereomeric pair between each enantiomer and a chiral reagent. There are two types of diastereomeric complex: long-lived and short-lived diastereomers. Short-lived diastereomers were discussed in the previous sections; such diastereomers occur between a pair of enantiomers and a chiral environment. Long-lived diastereomers are formed by chemical reaction between a pair of enantiomers and a chiral reagent. Supplementation of livestock feeds with certain amino acid enantiomers has generated interest in analyses of d- and l-amino acids. Amino acids have basic amino, acidic carboxyl groups; these affect their chromatographic behavior. Changing the pH of the mobile phase changes the amount of protonation or deprotonation of amino groups and the extent of dissociation of carboxyl group. Different chiral selectors have been used for thin layer chromatography resolution of variety of racemates of amino acids into enantiomers.