Consequences of a maximum existing in the dependence of separation selectivity on concentration of cyclodextrin added as chiral selector in capillary zone electrophoresis.
The maximum in the dependence of the separation selectivity on the concentration of cyclodextrin may be utilized for the determination of the mean value of host-guest interaction constants of the separated enantiomers. For the hosting of N-t-BOC-DL-tryptophan by beta-cyclodextrin, the mean value of these constants, found by drop line estimated from the cyclodextrin concentration corresponding at the maximum, is 350 L.mol-1. The separation at this concentration of cyclodextrin offers the highest resolution in the shortest separation time. It is shown that commonly used simple preliminary experiments, testing the capability of a cyclodextrin to resolve chiral compounds, and based on relatively high cyclodextrin concentrations, may easily lead to incorrect conclusions in cases of enantiomers strongly interacting with the cyclodextrin used.
Vespalec
R
R
Institute of Analytical Chemistry, Czech Academy of Sciences, Brno.
Fanali
S
S
Bocek
P
P
D003505:Cyclodextrins / Q000737:chemistry*; D004586:Electrophoresis / Q000295:instrumentation / Q000379:methods*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D014364:Tryptophan / Q000737:chemistry*
D003505:Cyclodextrins; D014364:Tryptophan