Retention on mixed cyclodextrin/polysiloxane stationary phases in capillary GC—Evidence for the interaction of cyclodextrin and polysiloxane

The dependence of the retention on stationary phases consisting of mixtures of a cyclodextrin (perpentyl-β-cyclodextrin) and a polysiloxane (cyanopropyl-7%-, phenyl-7%-methyl-86%-or OV-1701) was investigated as function of the cyclodextrin concentration. In order to study the effect of mixing, the data on the mixed stationary phases were compared with those obtained on pure OV-1701 and perpentylated β-CD and on coupled columns, individually coated with the pure phases. The validity of the retention model proposed in the literature by Schurig and co-workers was checked. Deviation from linearity was observed for some racemates. A possible explanation of the deviation is presented and a more general retention model on mixed cyclodextrin-polysiloxane phases is proposed.