Preparative-scale isoelectric focusing separation of enantiomers using a multicompartment electrolyzer with isoelectric membranes

The IsoPrime multicompartment electrolyzer, equipped with a series of isoel ectric membranes with closely spaced pi values, was used for the first time for the preparative-scale separation of the enantiomers of dansyl phenylal anine with hydroxypropyl beta-cyclodextrin as resolving agent. The final se paration conditions could be established easily in three successive experim ents by rationally narrowing the pH steps between the neighboring isoelectr ic membranes. The final separation yielded products with an enantiomeric ex cess greater than 99.9%, at production rates of about 0.1 mg/h. The greates t experimental difficulty was caused by the relatively high salt content of the hydroxypropyl P-cyclodextrin used, which resulted in high conductivity and limited the maximum field strength one could use.