Abstract: A method of partitioning a pre-selected phase of a sample of liquid having a plurality of phases of differing densities, a separating element and a tube containing the separating element. The sample of liquid is placed in a first chamber of a tube that is separated from a second chamber by a separating element. The separating element slidably engages the interior surface of the tube in a substantially fluid-tight manner. A fluid passage is disposed through the separating element and includes an initially closed fluid passage. The phases are ordered by axial centrifugation wherein the tube is rotated about its longitudinal axis, the separating element is moved within the tube reducing the volume of the first chamber, a pre-selected phase of the liquid is forced from the first chamber through the fluid passage into a second chamber. The reduction of the volume of the first chamber is controlled using phase-separation information. The separator may also include a filter for filtering the fluid.

Abstract: Apparatus for partitioning a pre-selected phase of a sample of liquid, such as blood, having a plurality of phases of differing densities. Disclosed is an apparatus for separating a pre-selected phase of a sample contained in an enclosed chamber, wherein said apparatus can be used with a separating means which rotates the chamber about either a longitudinal axis of the chamber, or about an axis perpendicular to the longitudinal axis of the chamber and not passing through the chamber. In addition, separating means in which such an enclosed chamber is rotated about a longitudinal axis is described. Also disclosed is an apparatus for dispensing fluid from said enclosed chamber.