Ultra-performance supercritical fluid chromatography and non-aqueous reversed-phase chromatography proved to be suitable techniques and alternatives for normal-phase chromatography for the enantioseparation of liquid crystals with chiral moiety based on lactic acid.
Fast, effective and complete enantioseparation of all five compounds with resolution values higher than 2 was achieved using tris(3,5-dimethylphenylcarbamate) derivative of amylose (see figure). Effects of the analytes structural differences and the mobile phase composition on the enantioseparation were assessed.
In SFC a strong correspondence between the number of analytes phenyl rings and its retention time was observed. Moreover, the presence of chlorine in the structure of analyte proved to have enhancing effect on the enantioseparation. The enantiomer elution order depended on the type of alcoholic modifier in the mobile phase with both techniques used. Additionally, the enantiomer elution order switching depending on portion of modifier was observed in non-aqueous reversed phase liquid chromatography and to some extent it also correlated with the length of the alcohol side chain.