Optimization of the separation of 1,1′-bi-2-naphthol enantiomers in preparative liquid chromatography

The separation of enantiomers of 1-1'-bi-2-naphthol on Pirkle covalent D-phenyl-glycine columns was investigated on the preparative scale. The adsorption characteristics of each isomer, including the equilibrium and kinetic model parameters, were measured by the elution chromatographic method. The competitive bi-langmuir model was adopted to correlate the adsorption equilibrium isotherms of the binary mixture. The numerical solution of the equilibrium-dispersive model of chromatography was used to predict the band profiles, where the isotherm parameters of the binary model were estimated by a model fitting method. The simulated band profiles can reasonably predict the measured chromatograms for various cases of different operating conditions, e.g. mobile phase composition, flow rate and sample size. The optimum operating conditions for the maximum production rate of either one of the two isomers were then found based on the theoretical model.