A method for the production of particles (P), said method comprising the steps of: a. providing - non-magnetic porous particles (Pp) having an exterior surface, pores and a connected interior surface defined by said pores, the porous particles (Pp) comprising at least one polymer, the porous particles (Pp) comprising at least one type of functional groups on said exterior and interior surfaces, and - magnetic particles (Mp) comprising at least one type of functional groups on their surface wherein the smallest diameter of at least 95wt% of all magnetic particles (Mp) is larger than the average diameter of the pores of the porous particles (Pp), and b. reacting functional groups on the surface of the non-magnetic porous particle (Pp), with functional groups on the surface of the magnetic particles (Mp) to form a covalent bond, to obtain particles (P) supplemented with magnetic particles (Mp) covalently bound to at least one selected from the interior surface and the exterior surface of the porous particles (Pp), wherein all of the at least one type of functional groups on the surface of the magnetic particles (Mp) have not reacted to form covalent bonds with the at least one type of functional groups on the exterior and interior surfaces of the porous particles (Pp) so that a fraction of the at least one type of functional groups remain available on at least one selected from the magnetic particles (Mp) and the porous particles (Pp), wherein the porous particles (Pp) comprise agarose, wherein the at least one type of functional groups on the exterior and interior surfaces the porous particle (Pp) are at least one selected from the group consisting of-SH, -S-S-pyridin, -COOH, -NH 2 , -CHO, -OH, phenol, epoxy, S-Au, and amide, wherein the at least one type of functional groups on the magnetic particles (Mp) include at least one selected from the group consisting of -SH, -S-S-pyridin, -COOH, -NH 2 , -CHO, -OH, phenol, epoxy, S-Au, and amide. a. providing - non-magnetic porous particles (Pp) having an exterior surface, pores and a connected interior surface defined by said pores, the porous particles (Pp) comprising at least one polymer, the porous particles (Pp) comprising at least one type of functional groups on said exterior and interior surfaces, and - magnetic particles (Mp) comprising at least one type of functional groups on their surface wherein the smallest diameter of at least 95wt% of all magnetic particles (Mp) is larger than the average diameter of the pores of the porous particles (Pp), and - non-magnetic porous particles (Pp) having an exterior surface, pores and a connected interior surface defined by said pores, the porous particles (Pp) comprising at least one polymer, the porous particles (Pp) comprising at least one type of functional groups on said exterior and interior surfaces, and - magnetic particles (Mp) comprising at least one type of functional groups on their surface wherein the smallest diameter of at least 95wt% of all magnetic particles (Mp) is larger than the average diameter of the pores of the porous particles (Pp), and b. reacting functional groups on the surface of the non-magnetic porous particle (Pp), with functional groups on the surface of the magnetic particles (Mp) to form a covalent bond, <EOS>