Abstract: A chromatographic method of separating a fluid mixture of dextrans of differing molecular weights into two fractions. The chromatographic method is carried out with an apparatus having a plurality compartments according to a scheme involving sequential valve operation and provision of carrier fluid.

Abstract: The invention provides a method of operating a chromatographic apparatus for separating a fluid mixture. The apparatus has a plurality of compartments containing a chromatographic packing, conduit means interconnecting the compartments in at least one closed loop series, isolating valves in said conduits for isolating each compartment from the remaining compartments, and, for each compartment, a valved purge fluid inlet, a valved purge fluid outlet, a valved carrier fluid inlet, a valved carrier fluid outlet, and a valved fluid mixture inlet. The valved fluid mixture inlet is adapted to be coupled to a source of a fluid mixture to be separated chromatographically.