Sol-gel technique for the preparation of beta-cyclodextrin derivative stationary phase in open-tubular capillary electrochromatography

A novel open-tubular capillary electrochromatography (OT-CEC) column coated with 2,6-dibutyl-beta -cyclodextrin (DB-beta -CD) was prepared using sol-g el technique. In the sol-gel approach, owing to the three-dimensional netwo rk of sol-gel and the strong chemical bond between the stationary phase and the surface of capillary columns, good chromatographic characteristics and unique selectivity in separating isomers were shown. We achieved high effi ciencies of 5-14 x 10(4) plates/m for the isomeric nitrophenols using the s ol-gel-derived DB-beta -CD columns. The migration time reproducibility of t he separation of the isomeric nitrophenols was better than 2.2% over five r uns and 4.5% from column to column. These sol-gel-coated DB-beta -CD column s have shown improved separations of isomeric aminophenols, isomeric dihydr oxybenzenes and isomeric nitrophenols, in comparison with the sol-gel matri x capillary column. The influences of buffer pH and methanol solvent on sep aration were investigated. The chiral resolution of enantiomers such as ibu profen and binaphthol was explored primarily.