PURPOSE: To reduce a determination time, by using porous particles made of sulfonates of homopolymer of divinylbenzene or copolymer of it and another hydrophobic monomer, having a limit value for exclusion of protein in a specified mol.wt.range. in order to omit a protein removal operation in separation and determination of low molecular components.

CONSTITUTION: The entitled filler is made of porous particles of sulfonates of homopolymer or copolymer, preferably having 340μm particle diameter, 5W50% voids, and 2,000W60,000 exclusion limit value (PL value). Protein is not retained in the pores of the filler particles when they have ≥2,000 of said value, and rapidly eluted out of the pores, and low-molecular components retained in the pores are eluted delayed than the protein, and among those components they are separated from each other by the difference in ion exchange ability.