Simulated moving bed (SMB) chromatography involving a series of columns serially connected in a circuit is performed in a modified protocol by dividing the columns into two groups isolated from flow communication with each other and using one of the two groups solely for extraction of the more strongly retained component from the solid phase while the other group is operated in the conventional SMB manner. The sites of introduction and withdrawal and the site of division between the two groups of columns are all rotated around the circuit as in conventional SMB chromatography, but the process is capable of separating component mixtures with non-linear isotherms and of extracting solutes that are very strongly retained on the solid phase.