AbstractThe enantiomeric resolution of six closely related hexa‐ and octa‐hydrobenzo(g) quinoline racemates by HPLC on an ovomucoid column (Ultron ES‐OVM) is described. First, the influence of uncharged mobile phase additives (with different hydrogen bonding properties) and pH on retention and enantioselectivity is investigated. It is shown that an optimum pH of around 6 for the given separations is much more important than the choice of modifier. Second, the influence on enantioselectivity of small differences in molecular structure is examined. In one case a large difference is obtained for diastereomeric racemates depending on the cis‐ or trans‐configuration of the quinoline skeleton. Higher flexibility of the solute seen in the cis enantiomers seems to improve enantioselectivity. © 1993 Wiley