Continuous enantiomer separation of the Volatile inhalation anesthetic enflurane with a gas chromatographic simulated moving bed unit

The separation of the enantiomers of the racemic inhalation anesthetic enflurane was achieved by continuous gas phase simulated moving bed chromatography (GC-SMB). The productivity of the unit and the enantiomeric excess of the obtained streams were somehow low mainly because of the high operating temperature, i.e., T=50 degrees C. As chiral stationary phase, an unpurified cyclodextrin derivative, consisting of various isomers and homologues and dissolved in an apolar polysiloxane matrix, was used. The competitive adsorption isotherms of (R)-(-)-enflurane and (S)-(+)-enflurane were determined by gas chromatographic measurements at increasing values of the pulse concentration in the range from linear to overload conditions. It has been shown that the adsorption behavior of the two enantiomers can be explained by considering enantioselective and non-enantioselective sites on the stationary phase. These results demonstrate the feasibility of the chiral resolution of enflurane by GC-SMB. (C) 1998 Elsevier Science B.V. All rights reserved.