Whitham & Marhoefer
Centrifuge vessel with coaxial waste chamber having cap to prevent waste fluid transfer from the chamber into the vessel
 A centrifuge vessel for performing immunoassays, affinity chromatography, and like experiments includes a center tube and an outer waste chamber. A biomaterial is held within the center tube and is capable of binding specific analytes in test samples. In operation the centrifuge vessel is rotated at high speed about its longitudinal axis, thereby causing all fluid within the center tube to be transported into the outer waste chamber while the analyte of interest remains bound to the biomaterial positioned within the center tube In the centrifuge vessel, a cap connected to the outer waste chamber and extending over the center tube includes structure for preventing waste fluid expelled to the waste chamber from re-entering the center tube. In a first embodiment, the cap is either constructed from or the inside surface is coated with a hydrophobic material which repels fluids back into the waste chamber. In a second embodiment, the cap includes a dam which allows fluid to pass into the waste chamber but blocks the migration of waste fluid back to the center tube. In a third embodiment, the cap includes a sponge that allows fluids in the center tube influenced by the intense centrifugal forces generated during high speed rotation to pass into the waste chamber, but which prevents fluids in the waste chamber, which are influenced by relatively weaker forces, from returning to the center tube. 
Cirrus Diagnostics, Inc.
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Arthur L. Douglas R. Thomas
Rabson Olson Palmieri