Cyclodextrin neutral derivatized

The extracts contained almost pure pheromone, with only minor amounts of other components. By comparison with synthetic samples, derivatization, and gas chromatography on a chiral cyclodextrin phase, the pheromone was identified as a 95 5 mixture of (5)- and (/ )-enantiomers of dimethyl citrate (cupilure (3), Fig. 4.2). Only the (5)-enantiomer was active (Tichy et al., 2001). Cupilure is probably present in ionized form on the silk (pK 3.5), because solvent extracts were neutral. The ionized carboxyl group may be conjugated to basic amino acids of the silk proteins. This would also explain why the pheromone is not volatile, despite its relatively low molecular weight, and is easily washed from the silk by water, including rain. In the tropical habitat of C. salei this would ensure the presence of cupilure only on freshly laid silk. 

NEUTRAL CYCLODEXTRINS The above-mentioned native cyclodextrins, a-CD, (3-CD, and y-CD, can be considered neutral in the pH range commonly used in CE. Derivatized CDs can also be neutral when neutral groups, such as methyl, hydroxyethyl, and hydroxypropyl, are incorporated. 

Several chiral selectors can be added to the background electrolyte and used in capillary electrophoresis. The most common selectors are the cyclodextrins, native and mainly derivatized. For the past five years, numerous applications with these chiral selectors have been described in the literature. Cyclodextrins can be neutral or positively or negatively charged, allowing them to discriminate between charged and neutral compounds. 

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