Improved preparative-scale continuous free-flow electrophoretic separationof the enantiomers of terbutaline utilizing equal-but-opposite enantiomer mobilities

The factors that influence yield and product purity in the continuous, prep arative-scale electrophoretic separation of the enantiomers of terbutaline when using the principle of equal-but-opposite effective mobilities were st udied. The sodium salt of heptakis-6-sulfato-beta -cyclodextrin was used as the resolving agent, in acidic, isopropanol-containing background electrol ytes, in the continuous, free-flow, preparative electrophoretic instrument, the Octopus. By matching the linear velocity of the feed solution to that of the background electrolyte, lateral hydrodynamic dispersion was minimize d resulting in a nonelectrophoresed feed band that was only three fractions (about 3 mm) wide as it exited the 0.5 mlong separation channel. The multi ple of residence time and applied potential was also optimized, constrained by migration of the front of heptakis-6-sulfato-beta -cyclodextrin out-of the separation zone, leading to the recovery of 95% of both enantiomers in better than 99.99% purity, at a production rate of 0.1 mg/h.