Strong cation exchange chromatographic matrix and method for using same

A purification method for purifying a physiologically active substance from a mixed solution containing impurities and the physiologically active substance, comprising

• contacting the mixed solution with a cation exchange chromatographic matrix for biomolecule purification, wherein the cation exchange chromatographic matrix comprises:
• a base material, and
• a copolymer with one monomer unit having at least a sulfonic acid group, the copolymer being on a graft chain immobilized on the base material wherein:
• the copolymer forms substantially no cross-linked structure, and the copolymer comprises neither acrylamide nor an acrylamide derivative as a monomer unit, or comprises acrylamide or an acrylamide derivative as a monomer unit at a mass percent of 10% or less based on all monomer units of the copolymer;
• the ratio of the mass of the copolymer to the mass of the base material is 5% or more and 200% or less;
• the density of the sulfonic acid group is higher than 30 mmol/L and 200 mmol/L or lower;
• the mixed solution is contacted with the matrix in a flow-through mode;
• and
• a mass of graft chain per the cation exchange chromatographic matrix volume is 0.03 g/mL or larger and 0.25 g/mL or smaller, wherein the mass of graft chain per the cation exchange chromatographic matrix volume is represented by the following expression:
• sg(g/mL)=(w2−w0)/v1
• wherein w2 is the mass of the cation exchange chromatographic matrix obtained as a final product, v1 is the volume of the cation exchange chromatographic matrix obtained as the final product, and w0 is the mass of the base material before introduction of the graft chain.