NEW MATERIAL: An antigen composite formed by covalently bonding a haptene to a protein carrier through a linker represented by the formula (wherein Ch is chalcogen (O, or S); m is 2-20; n is 2-20; and R' is H or a reactive group capable of participating in bonding to protein of the linker).

USE: An immunogen for producing an antibody.

PROCESS: For instance, a fluorocarbon-chain-contg. antigenic conjuage is obtd. by reacting a haptene (e.g. acetobromogalactose) with a linker (e.g. methyl 5-hydroxy-2,2,3,3,4,4-hexafluoropentanoate) in a solvent (e.g. methylene chloride) and then with a protein carrier (e.g. human serum albumin) in water and dialyzing the resultant product against distilled water.