Chromatographic Separation of Chiral Drugs in a Diallyl-L-tartardiamide-based Stationary Phase: Influence of Temperature on the Equilibrium and Mass-Transfer Parameters

Abstract

The influence of temperature on the equilibrium and mass-transfer parameters in the chromatographic separation of bupivacaine enantiomers was evaluated using a chiral stationary phase (CSP) based on diallyl-L-tartardiamide (Kromasil® CHI-TBB). The total and bed porosities as well as the linear equilibrium constant were obtained by pulse experiments using dilute solutions of inert compounds and bupivacaine enantiomers at different flow rates (1.0, 2.0, 3.0 and 4.0 m l /min) and temperatures (25, 35 and 45°C). The axial dispersion and overall mass-transfer coefficients were evaluated by van Deemter plot. A decrease in the linear equilibrium adsorption constants with increasing temperature was observed for both enantiomers. This chiral column showed good separation performance with a high order of magnitude for the overall mass-transfer coefficient. These values increased with increasing temperature. However, it was not possible to differentiate between these values at different temperatures due to poor standard deviations. Because of the high order of magnitude of the overall mass-transfer coefficient associated with a good resolution of bupivacaine enantiomers, it was concluded that convection effects dominated chiral separation in this column.