PURPOSE: To obtain a high separation performance for a wide range of material group with a higher acid resistance, by employing chlorinated apatite for 5W100mol.% of particle components in a packing agent for liquid chromatography.

CONSTITUTION: A packing agent for liquid chromatography employs chlorinated apatite for 5W100mol.% of particle components. The chlorinated apatite is as shown by Ca10(PO4)6(OH)2-2xCl2x (x is 0.05W1) and can be manufactured by synthetic or ion exchange method. In the case by the synthetic method, phosphoric acid is dropped into a liquid containing calcium and chlorine, and a solid material obtained is pelletized to obtain chlorinated apatite by calcination. In the case by the ion exchange, a hydroxyapatite particle is dipped into an aqueous solution containing chlorine ions to make an ion exchange of a part of hydroxide group with chlorine and after a drying, heat processing is performed.