Patent ID: 8540082

Claim:
A centrifugal assembly for separation of buoyant material, comprising: a tube configured for containing a floatation fluid and a sample of matter to be separated, wherein the tube is elongated with respect to an axis and includes an open upper end and a closed lower end; and a meniscus-forming device engageable with and movable along the tube with respect to the axis, the device comprising an insert configured for sealing engagement with an interior surface of the tube, the insert including a sleeve depending within the tube and defining an interior region, the insert further including an open upper end disposed above the upper end of the tube at which a meniscus is formable, the sleeve having a volume sized to displace a volume of the floatation fluid in the tube upwardly to form a meniscus at the open upper end of the insert when the insert is moved a distance downwardly along the tube, and a filter element disposed to prevent passage of material of a size greater than openings in the filter element into at least a portion of the interior region of the sleeve.