Comparison of enantioselective separation of N-tert.-butyloxycarbonyl amino acids and their non-blocked analogues on teicoplanin-based chiral stationary phase

A teicoplanin-based chiral stationary phase (CSP) was tested for enantiosep aration of underivatized amino acids and their N-tert.-butyloxycarbonyl (t- Boc) derivatives, important precursors in peptide synthesis. Mobile phase c omposition was optimised for organic modifier and triethylamine acetate buf fer (TEAA) contents, and retention and enantioresolution of t-Boc-amino aci ds and their non-blocked analogues were compared. The importance of the ami no group of amino acids in the interaction mechanism was evaluated. Native amino acids have better possibility for interaction with teicoplanin; they are more retained on the CSP and better enantioresolved than the blocked am ino acids. Presence of triethylamine in the aqueous portion of the mobile p hase was shown to be important for separation of enantiomers of t-Boc-amino acids; while native amino acids were almost not affected by the addition o f TEAA. Results obtained for blocked amino acid on teicoplanin CSP with mob ile phase composed of 1% triethylamine acetate, pH 4.1 and organic modifier were compared to those got on hydroxypropyl-beta-cyclodextrin CSP. Good en antioseparation in a reasonable analysis time was obtained on the teicoplan in-based chiral stationary phase, (C) 1999 Elsevier Science B.V. All rights reserved.