Polar-liquid, derivatized cyclodextrin stationary phases for the capillary gas chromatography separation of enantiomers.

A new class of hydrophilic, relatively polar liquid, cyclodextrin (CD) derivatives have been used as highly selective chiral stationary phases (CSPs) for capillary gas chromatography (GC). Several possible requirements for liquidity in CD derivatives are discussed. O-(S)-2-Hydroxypropyl derivatives of alpha-, beta-, and gamma-cyclodextrins were synthesized, exclusively characterized, permethylated, and evaluated for enantioselectivity. Seventy pairs of enantiomers were resolved. They represent a wide variety of structural types and classes of compounds including chiral alkyl amines, amino alcohols, epoxides, pyrans, furans, sugars, diols, esters, ketones, bicyclic compounds, alcohols, and so on. Many of these compounds were not aromatic and cannot be resolved on any known liquid chromatographic CSP. Often, these enantiomers had far less functionality than required for LC separation. General properties of these CSPs as well as possible insights into the separation mechanism are discussed.