[en] A magnetically assisted sample preparation process for capturing and separating trace Np was established. With the application of TiOA paramagnetic capture, the sample can be prepared quickly while concentration and separation are all done. The influences of reacting time, the mass of capture, the volume and acidity of aqueous phase on the sample preparation were studied. The detection limit of this method for Np is 0.12 μg. The mass concentration detection limit is 0.04 mg/L, which meets the requirements of analyzing Np by XRF at 3EU in Purex. (authors)