Effects of mobile phase composition on key parameters for the design of preparative chromatography separation of equol enantiomers

• Mobile phase composition has contradicting effects on key parameters for SMB separation of equol enantiomers. • Competitive adsorption can be described with bi-Langmuir model. • Mass transfer coefficients exhibit maxima at ethanol volumetric ratio of 0.35. • Equol concentration of is limited by the formation of two split liquid phases. • Composition effects on these parameters are described with concise and continuous correlations. Key parameters and their dependence on mobile phase composition for the design of preparative chromatography separation of equol enantiomers were investigated. Temperature is fixed at 298 K, the stationary phase is ChiralPak AD, and the mobile phases are n-hexane/ethanol mixtures with ethanol in the range of 20–40 v%. Linear pulse experiments carried out at various flowrates were firstly used to determine Henry’s constants, axial dispersion and mass transfer coefficients. A total of 6 parameters of bi-Langmuir competitive isotherm model, with one of the parameters accounting for mobile phase composition effects, were acquired by inverse method on plateaus. Maximum racemate concentrations for complete miscibility were also measured at 298 K. Composition effects on these parameters were described with explicit and continuous correlations.