ENANTIOMERIC SEPARATION OF ALCOHOLS BY GAS CHROMATOGRAPHY USING BETA-CYCLODEXTRIN DERIVATIVE AS STATIONARY PHASE

Abstract

Enantiomeric separation of forty alcohols based on 1-phenylethanol was studied by gas chromatography using heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-ß-CD (or BSiAc) as a chiral stationary phase. Factors affecting analyte retentions and enantioselectivities were studied: column temperature, alcohol structure (type and position of substitution) as well as type of alcohol derivatization (trifluoroacetyl (TFA) and trimethylsilyl (TMS)). The number of underivatized alcohols that could be separated into their enantiomers was higher than those of derivatized forms. Temperature affected enantioselectivities of meta-substituted underivatized alcohols more than para- or ortho-isomers, while it affected enantioselectivities of para-substituted derivatized alcohols more than other isomers. However, derivatization could improve enantioseparation of some alcohols and may provide more symmetrical peak shapes. In addition, many TFA derivatives showed complete enantioseparation in shorter analysis time than their corresponding underivatized alcohols. In this study, enantiomeric separation of all analytes, either underivatized or derivatized form, could be observed. The shortest analysis time for complete enantioseparation was observed for 18-TFA.