A method for separating biological materials and other substances is disclosed, wherein a mixture containing desired and undesired components are exposed to magnetic particles having ligands capable of binding to the desired and/or the undesired components to form a magnetic mixture, placing the magnetic mixture onto a substrate material; exposing the substrate coated with the magnetic mixture to a magnetic field of sufficient strength to cause the magnetic components to migrate across the substrate; and repeatedly increasing and decreasing the magnetic field in a pulsing manner with a frequency sufficient to cause the desired magnetic components to separate spatially from the undesired magnetic components. A device for separating biological materials capable of being operated to increase and decrease magnetic field in a pulse fashion is also disclosed.