High-performance liquid chromatographic enantioseparation of N-protected ?-amino acids using nonporous silica modified by a quinine carbamate as chiral stationary phase

Abstract

In this study, tert-butyl carbamoylated quinine as chiral selector was immobilized on nonporous silica (NPS) 1.5 μm particles developed by MICRA, and this new chiral stationary phase (CSP) was packed into a 3.3 cm column (4.6 mm ID). A series of various N-protected α-amino acids was chosen as chiral selectands, including 3.5-dinitrobenzyloxycarbonyl amino acids (DNZ-AAs). In order to optimize the chromatographic conditions with this novel CSP and to apply it to the resolution of acidic analytes the following parameters have been varied and studied: pH of the mobile phase, buffer concentration, and percentage of methanol or acetonitrile in the mobile phase. DryLabR software was applied to optimize enantioseparation by simulating chromatographic functions of experimental conditions for isocratic and/or gradient runs. Thus, we were able to resolve a set of test compounds within several minutes, whereby our attention was particularly drawn to the resolution of DNZ-AA derivatives. Chirality 9:157–161, 1997. © 1997 Wiley-Liss, Inc.