Capillary Chromatography - Applications of Capillary Columns in GC Analysis 4
Courtesy of Supelco
Figure 27. A Molecular Model of Cyclodextrin
The thermal stability of the mixed stationary phase can be improved by incorporating a phenylpolysiloxane into the coating material. Phenylpolysiloxane also significantly improves the stability of the coating to oxidation, particularly at elevated temperatures (as cyclodextrin is basically a sugar, is will be very susceptible to oxidation at high temperatures). Some methysiloxane, however, must still be present to render the cyclodextrin soluble in the polymer matrix. Chiral selectivity can be further augmented by bonding other chirally active groups onto the secondary hydroxyl groups of the cyclodextrin (see again figure 27). Unfortunately, much of the chemistry used to derivatize these cyclodextrin compounds is considered proprietary and so synthetic details are not readily available.