Method of chromatographic separation

Claim 1

In a method for separating respective substances in a feedstock fluid with a chromatographic apparatus including a packed bed in which fluid flows cyclically in one direction and which further includes a plurality of fluid inlets and fluid outlets, including a feedstock fluid supply inlet, a nonadsorbate fluid extraction outlet, a desorbent fluid supply inlet, and a adsorbate fluid extraction outlet, disposed in that order along the direction of fluid flow, said bed, taken as a whole, being divided into four zones: an adsorption zone, occupying a space between the feedstock fluid supply inlet and the nonadsorbate fluid extraction outlet; a refining zone, occupying a space between the nonadsorbate fluid extraction outlet and the desorbent fluid supply inlet; a desorption zone, occupying a space between the desorbent fluid supply inlet and the adsorbate fluid extraction outlet; and a concentration zone, occupying a space between the adsorbate fluid extraction outlet and the feedstock fluid supply inlet, one supply inlet/extraction outlet pair being switched to another supply inlet/extraction outlet pair located downstream thereof after a predetermined working time, the improvement wherein the following two steps are performed within said predetermined working time: (i) a supply and extraction step in which, as part of the fluid flowing out of the desorption zone is extracted from the packed bed through the adsorbate fluid extraction outlet and the remainder flows into the concentration zone while the fluid flowing out of the concentration zone flows into the adsorption zone, a feedstock fluid and a desorbent fluid are supplied into the packed bed through the feedstock fluid supply inlet and the desorbent fluid supply inlet, respectively, and substantially all of the fluid flowing out of the adsorption zone is extracted from the packed bed through the nonadsorbate fluid extraction outlet, such that an amount of the fluid extracted through the nonadsorbate fluid extraction outlet is greater than an amount of feedstock fluid supplied, and an amount of the fluid extracted through the adsorbate fluid extraction outlet is less than an amount of desorbent fluid supplied; and (ii) a circulation step in which the fluid in the packed bed is moved downstream without supplying a fluid into or extracting a fluid from the bed.