Chromatographic separation

A method for fractionating a solution into two or more fractions by a sequential chromatographic SMB process with equipment comprising a feed column and one or several other columns connected in series, said feed column and said other columns including a chromatographic separation resin bed, wherein said fractions are recovered during a multi-step sequence comprising a feeding phase, an eluting phase and a circulation phase, characterized in that there is achieved a decreased tailing effect of the separation profile in the fractionation by carrying out said feeding phase on a feed column consisting of or comprising a compartment where the resin bed is shallower than that of one or more of the other columns of the equipment and wherein the height of the resin bed of said shallow resin bed compartment is equal to or less than 12.5% of the total height of the resin beds of the columns of the equipment.