A beta-cyclodextrin-bonded phase has been used to investigate the sepa
ration of the enantiomers of atenolol, oxprenolol, celiprolol, tertato
lol, terbutaline, fluoxetine, norfluoxetine, and zopiclone, focusing o
n the importance of solvent selectivity. With cyclodextrin (CD)-bonded
phases, chiral discrimination occurs because the two enantiomers of a
racemate form inclusion complexes of different strengths within the C
D cavity. The organic modifier molecules tend to compete with solutes
for a definite number of adsorption sites on the stationary phase. Mor
eover, the ternary complex formation may play an important role in chi
ral recognition. In this study, it was of interest to estimate the inf
luence of mobile phase modifiers with respect to solvent type (i.e., A
CN, MeOH, EtOH, THF, i-PrOH, PrOH and t-BuOH), size and shape, and con
centration. Solvent selectivity has been investigated by using differe
nt organic modifiers in mobile phases with the same polarity, and rela
tionships were established between the logarithm of solvent partition
coefficient (log P-s) and the three most important chromatographic par
ameters: retention time (t), resolution (R), and enantioselectivity (a
lpha). Thus, it seems that the hydrophobicity of the organic modifier
becomes one of the dominant factors affecting the inclusion process ph
enomena. Further, the apparent partition coefficients of the compounds
under study have been determined and a comparison has been attempted
regarding the degree of their enantiomeric resolution. (C) 1995 Wiley-
Liss, Inc.