Gas chromatographic separation of amino acid enantiomers and their recognition mechanism on a 2,6-di-O-butyl-3-O-trifluoroacetylated-γ-cyclodextrin capillary column

Abstract Some amino acids and 2- and 3-hydroxybutyric acid derivatives were resolved on a chiral capillary column coated with 2,6-di-O-butyl-3-O-trifluoroacetylated-γ-cyclodextrin, and their thermodynamic data were obtained from this stationary phase. Obvious differences in Δ(Δ H °) and Δ(Δ S °) were observed among these amino acids. The enthalpy-entropy compensation and structural effects were analysed with consideration of chiral recognition. The results suggested that the induced conformation fit between enantiomers and cyclodextrin derivatives could be important in chiral recognition. The enantiomers with large negative Δ(Δ H °) and Δ(Δ S °) values could form inclusion complexes and the separation of enantiomers with small negative Δ(Δ H °) and Δ(ΔS°) values could be due to other types of interactions.