Chiral supercritical fluid chromatography on porous graphitic carbon usingcommercial dimethyl beta-cyclodextrins as mobile phase additive

Using dimethylated-p-cyclodextrin mixtures (MeCD) as chiral selectors in CO 2-polar modifier mobile phase and porous graphitic carbon as solid-phase, c hiral supercritical (or subcritical) fluid chromatography was performed. Th e adsorbed quantity of MeCD onto the porous graphitic carbon (Hypercarb) wa s measured for various chiral selector concentrations using the breakthroug h method with evaporative light scattering detector. The effects of MeCD co ncentration in the mobile phase, the nature of the polar modifier, the outl et pressure, the column temperature and the nature of the commercial MeCD m ixture on the retention and the enantioselectivities were studied. For a gi ven solute, the enantioselectivity is greatly dependent on the commercial M eCD mixture used. The retention mechanism was also studied. From the data, we find that the dominant mechanism for the chiral discrimination is the di astereoisomeric complexation in the mobile phase. (C) 2001 Elsevier Science B.V. All rights reserved.