Cyclodextrins with heterocyclic substitution as GC stationary phases

Two new cyclodextrin (CD) derivatives, heptakis {2,6-di-O-pentyl-3-O-[3 '-(2''-chloro-4'',5''-dioxylmethene)-phenyl-5 '-iso-oxazolylmethyl]}-β-CD (CD I) and heptakis {2,6-di-O-methyl-3-O-[3' '-(2''-chloro)-phenyl-5'-iso-oxazolylmethyl]} -β-CD (CD II) were synthesized and coated on fused-silica capillary columns. Their chromatographic characteristics, including column efficiency, polarity, selectivity and phase transition were studied and compared with similar β-CD stationary phases. It was found that the heterocycle group has a significant effect on the selectivity of the CD stationary phases. Both stationary phases can be successfully used to separate many di- and trisubstituted benzene positional isomers and show stronger separation ability in separating low-polarity benzene positional isomers than other β-CD stationary phases.