Abstract: A centrifuge tube is used to hold a mixture of several constituents, and also contains a generally cylindrical float. The float settles, after centrifugation, into the zone occupied by the constituent whose volume is to be measured. The constituent layer will settle, after centrifugation, into the annular space between the tube bore and the outside of the float, and will be expanded axially due to the restricted volume of the annular space. The degree of expansion is dependent upon the respective sizes of the float O.D. and the tube bore ID, both of which must be closely controlled for accurate results. A known volume of a control material is placed in the tube to settle into the annular space during centrifugation in an area thereof outside of the constituent layer zone. The length of the band of the control material is measured after centrifugation and is compared to a known length which will result if the annular space is of the proper target volume.

Abstract: In order to produce a more well defined interface between adjacent cell layers in a centrifuged sample of anticoagulated whole blood, a material which will bond one group of cells together is added to the blood sample prior to centrifugation. The bonding material must produce a high strength bond between one group of cells, but not effect the other cell types. The material is added prior to centrifugation of the blood sample. An example of a bonding agent is a monoclonal antibody.