| abstract |
A magnetic composite body comprising magnetic nanoparticles having a number average particle diameter of 1 to 50 nm and having a compound represented by formula (I) fixed on their surfaces, and a method comprising bringing the magnetic composite body into contact with a test piece followed by magnetic separation: Formula (I) R1O-(CH(R2)CH2O)n-L-X wherein R1 represents a hydrogen atom, an alkyl or alkenyl group having a carbon chain length of 1 to 20, or a substituted or unsubstituted, aryl or heterocyclic group; R2 represents a hydrogen atom or a methyl group; L may be present or not present, and, when L is present, L represents an alkylene or alkenylene group having a carbon chain length of 1 to 10 which may have a branched chain or a substituent; X represents a hydrogen atom, a carboxylic acid group, a phosphoric acid group, or a sulfonic acid group; and n represents an integer of 1 to 10 |