Patent ID: 7629176

Claim:
An apparatus for separation and analysis of a target analyte in an expanded buffy coat layer of a sample of anticoagulated whole blood, comprising: a self-supporting flexible tube for holding the sample, the sample tube having an elongate side wall with an inner surface; and an elongate, rigid, volume-occupying float having a specific gravity intermediate that of red blood cells and plasma, said float comprising: a main body portion spacedly surrounded by said inner surface of the side wall to form an annular volume therebetween; a flat top support member protruding from and defining a top axial end of the main body portion; a flat bottom support member protruding from and defining a bottom axial end of the main body portion, the top and bottom support members continuously traversing the annular volume and engaging said inner surface of said side wall to produce one or more analysis areas; and relief means for inhibiting excessive fluid flow through the expanded buffy coat layer during centrifugation deceleration; wherein said side wall is resiliently radially expandable in response to centrifugal force to permit axial movement of the float in the tube and fluid flow therearound during centrifugation and, upon deceleration, capturing the float and trapping the analyte in the expanded buffy layer in the analysis area.