Diluted modified cyclodextrins as chiral capillary gas chromatographic stationary phases: Influence of the polysiloxane solvents on enantioselectivity and column efficiency

The influence of different polysiloxane solvents on the efficiency and stereoselectivity of columns coated with mixtures of heptakis(2,3‐di‐O‐methyl‐6‐O‐tert‐butyldimethylsilyl)‐β‐cyclodextrin (DIME‐6‐TBDMS‐β‐CD) and the polysiloxanes was investigated. In the case of DIME‐6‐TBDMS‐β‐CD, the enantioselectivity of the chiral selector is strongly influenced by the polysiloxane used as diluting phase. Enantioselectivities achieved using apolar polysiloxanes are usually higher than those obtained with increased cyclodextrin content in a more polar polysiloxane, without the drawback of reduced column efficiency resulting from high cyclodextrin content. Changing the polarity of the polysiloxane can also be useful for limited “selectivity tuning” of the chiral stationary phases, for resolving randomly co‐eluting peaks.