Abstract: Disclosed is a method for separating a blood material into blood components by centrifugation, wherein when a multiple blood bag unit including a plurality of flexible blood bags (at least one of the flexible blood bags containing a blood material) liquid-tightly connected to at least one leukocyte-removing filter device through flexible tubes in a predetermined order is accommodated in a centrifuge bucket, at least the blood material-containing flexible blood bag or bags are inserted in the centrifuge bucket while placing at least the leukocyte-removing filter device outside of the centrifuge bucket, wherein the leukocyte-removing filter device is directly or indirectly secured relative to the rotor and a center of the filter device is located at a distance from an axis of the rotation shaft which is smaller than a distance between a pivotal axis of the turning of the centrifuge bucket and an axis of the rotation shaft at a portion thereof which has the rotor connected thereto.

Abstract: A novel hydrophilic composite porous membrane is obtained by applying a specific copolymer solution onto the overall surface of an oriented polyolefin membranous matrix comprising a plurality of microfibrils and a plurality of knotted portions cross-connected to the microfibrils, followed by drying. The copolymer is water-insoluble and is comprised of hydrophilic monomeric units and hydrophobic monomeric units in a specific ratio. In the obtained composite porous membrane, the microfibrils are bonded together by means of the copolymer, thereby forming bundles and a coat of the copolymer is formed on the overall surface of the bundles and knotted portions. The membrane has therewithin pores which are substantially elliptic in the cross section taken along the same direction as the longitudinal direction of the microfibril bundles and has on both surfaces thereof openings which are substantially elliptic as viewed against the surface of the membrane.

Abstract: A compact plasma separator comprises a casing provided with a blood introduction opening, a blood withdrawal opening and at least one opening for plasma withdrawal. A bundle of porous hollow fibers is disposed in the casing and fluid-tightly connected at end portions thereof to the blood introduction opening and the blood withdrawal opening. The porous hollow fibers have an average effective length not greater than 200 mm and a membrane surface area not greater than 0.3 m.sup.2, and the average effective length (L mm) satisfies the following relationship:L/D.sup.2 (mm.sup.-1).gtoreq.2000in which D represents an average inner diameter of the porous hollow fibers. The compact plasma separator can easily be constructed into an apparatus which can be practically employed for separating plasma from whole blood.