CHIROSPECIFIC ANALYSIS IN FLAVOR AND ESSENTIAL OIL CHEMISTRY .B. DIRECT ENANTIOMER RESOLUTION OF TRANS-ALPHA-IONONE AND TRANS-ALPHA-DAMASCONE BY INCLUSION GAS-CHROMATOGRAPHY

The direct capillary gas chromatographic separation of trans-alpha-ionone and trans-alpha-damascone enantiomers is reported using heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin in polysiloxane as a suitable chiral stationary phase. The method described has been applied to determine the naturally occurring enantiomeric composition of trans-alpha-ionone in the absolutes of the flowers of Boronia megastigma Nees and Osmanthus fragrance Lour., Costus root oil (Saussurea lappa Clarke) as well as in odor concentrates of violet flowers (Viola odorata L.), fresh raspberries, carrots and vanilla pods. Furthermore, the optical purity of trans-alpha-ionone in the solvent extracts of distilled alcoholic raspberry beverage, raspberry fruit juice concentrate and black tea was investigated. Trans-alpha-ionone was either isolated by headspace stripping in vacuo or by organic solvent extraction and subsequently enriched by multidimensional preparative chromatographic techniques. Trans-alpha-damascone was isolated from Virginia tobacco extract and from black tea aroma and was enriched for direct chirospecific analysis by medium pressure liquid chromatography followed by multidimensional preparative capillary gas chromatography. The importance of chirality as an essential criterion for the discrimination of natural and nature-identical aromas is discussed briefly.