Fast UHPLC enantioseparation of liquid crystalline materials with chiral center based on octanol in reversed-phase and polar organic mode

Abstract

Fast baseline enantioseparation of twenty racemic liquid crystalline compounds was carried out via ultra-performance liquid chromatography through direct enantioseparation in polar organic and reversed-phase modes. Tris(3-chloro-5-methyl-phenylcarbamate) derivative of amylose was used as chiral stationary phase; the chiral selector was covalently immobilized on sub-2 µm silica particles. Experiments were done using either pure acetonitrile as mobile phase or simple binary mobile phases consisting of acetonitrile/water mixtures in different volume ratios. No buffers or additives were used. Studied materials are a set of structurally similar compounds comprising two different structures of chiral center, various length of alkoxy spacer and four patterns of lateral substitution of aromatic core by fluorine. The compounds do not contain any ionizable group. The effect of the enantiomer structure on the retention and enantioseparation was evaluated. Flow rate and column temperature were optimized as part of method development.