CYCLODEXTRIN DERIVATIVES IN THE GAS-CHROMATOGRAPHIC SEPARATION OF RACEMIC MIXTURES OF VOLATILE COMPOUNDS .7. THE USE OF 2,6-DI-O-METHYL-3-O-PENTYL-BETA-CYCLODEXTRIN DILUTED IN PHASES WITH DIFFERENT POLARITY IN THE SEPARATION OF RACEMATES IN COMPLEX-MIXTURES

In the GC separation of volatile racemates, cyclodextrin (CD) derivatives may be used either as such or diluted in polysiloxane. If diluting phases with different polarity are used, different interactions and as a consequence a different retention of each component in a complex mixture are produced. The combination of the retention indices from columns coated with a CD derivative diluted in different polysiloxane phases makes it possible to locate and to identify unambigously the enantiomers of an optically active compound in a complex mixture and hence from their areas to determine directly the enantiomeric excess (e.e.). Some examples in the fields of essential oils and aromas illustrate the abilities of 2,6-di-O-methyl-3-O-pentyl-beta-CD diluted with different phases (PS-347.5, PS-086, OV-1701 and OV-1701-OH) to evaluate the e.e. of one or more optically active compounds in a complex mixture.