Chromatographic separation of racemic amino acids by use of chiral crown ether-coated reversed-phase packings.

Chromatographic packings for optical resolution of underivatized racemic amino acids were prepared by dynamic coating of a chiral crown ether on reversed-phase packings, and their characteristics were examined. Almost all the amino acids commonly found in proteins were finely separated into their enantiomers when a dilute aqueous solution of perchloric acid was used as the eluent. The enantiomers forming more stable complexes with the chiral crown ether were eluted after those forming less stable complexes. The retention and resolution of racemic amino acids depended on the eluent, the column temperature and the amount of crown ether coated. The separation coefficients, alpha, increased with decreasing column temperature and/or with increasing amount of crown ether coated.