COMPARING THE OPTIMUM PERFORMANCE OF THE DIFFERENT MODES OF PREPARATIVE LIQUID-CHROMATOGRAPHY

A comparative study of the optimization of the different modes of the preparative separation of binary mixtures by liquid chromatography is presented. Band profiles were calculated by means of the equilibrium-d ispersive model of chromatography in the cases of isocratic elution, g radient elution, and displacement chromatography. The objective functi on to be maximized was the product of the production rate and the reco very yield. The production rate was calculated using the same definiti on of the cycle time in all cases. This common definition accounts for column regeneration after each run in each mode of the separation. Th e calculations reveal that the number of experimental parameters to be adjusted to achieve optimum separations is relatively small. The majo r parameters are the loading factor and the number of theoretical plat es, besides the displacer concentration in displacement chromatography , or the gradient steepness in gradient elution. The relative advantag es of the different modes of preparative chromatography are discussed. (C) 1998 Elsevier Science B.V.