Effects of the composition of the mobile phase on the production rate in reversed-phase overloaded chromatography

Band profiles in overloaded reversed-phase chromatography on octadecyl silica columns were calculated using the experimental parameters of the distribution isotherms of binary mixtures of (1) resorcinol and phenol and (2) phenol and o-cresol determined by binary frontal analysis with automatic, on-line analysis of the composition of the breakthrough curve plateaus. The dependencies of the isotherm coefficients on the concentration of methanol in aqueous-organic mobile phases were described by three-parameter equations and used in the numerical calculations. Calculated band profiles of the sample components allowed determination of the fraction range, recovery yield and production rate necessary to obtain the sample components in required purity with various loading factors and concentration ratios of sample components in dependence on the concentration of methanol in the mobile phase. It was found that there is an optimum composition of the mobile phase, at which the optimum production rate can be achieved, which depends on the isotherms and on the concentration ratio of components in the sample feed. (C) 1997 Elsevier Science B.V.