APPROACH TO THE THERMODYNAMICS OF ENANTIOMER SEPARATION BY GAS-CHROMATOGRAPHY - ENANTIOSELECTIVITY BETWEEN THE CHIRAL INHALATION ANESTHETICS ENFLURANE, ISOFLURANE AND DESFLURANE AND A DILUTED GAMMA-CYCLODEXTRIN DERIVATIVE

The thermodynamics of enantioselectivity, -Delta(D,L)(Delta G), -Delta (D,L)(Delta H), Delta(D,L)(Delta S) and T-iso, have been determined by gas chromatography employing the concept of the retention increment R ' for the inhalation anesthetics enflurane (1), isoflurane (2) and des flurane (3) and the selector (3-O-butanoyl-2,6-di-O-n-pentyl)-gamma-cy clodetrin (4) in the polysiloxane SE-54. It is shown that the separati on factor alpha is concentration-dependent. Therefore, the separation factor alpha should not be employed as a criterion for enantioselectiv ity in diluted systems. The -Delta(D,L)(Delta G) data for 1 and 4 are corroborated by H-1 NMR spectroscopic measurements.