Purification of magnetic microparticles was demonstrated, with a purification efficiency of (72±14) % at a flow rate of 3 μl/min, in a microfluidic chip using a rotational magnetic system under continuous flow conditions. The rotation of a periodically arranged magnetic assembly close to a fluidic channel carrying magnetic particles suspension allows the trapping and releasing of particles in periodical manner, leaving other particles to be discarded in the waste. Each trapping and releasing event resembles one washing cycle in a conventional biological assay.