An apparatus for mixing and separating magnetic particles in a liquid comprises a holder having a plurality of apertures configured as an array of rows and columns and a plurality of containers capable of receiving liquid containing magnetic particles, each container being sized to be placed in one of the apertures; plural magnets capable of being moved relative to the containers between a first position and a second position to change the position of the magnets and magnetic particles in the container; and a drive mechanism for moving the magnets between positions at a sufficiently high speed that the particles do not settle down due to gravitational forces during motion between the first and second positions.