Filter for centrifuge tube

A filter assembly for filtering materials by means of centrifugal force, said assembly comprising:

• a centrifuge tube comprising a cylindrical tube of a first length which is closed at a lower end and open at an upper end and including an upper portion adjacent the upper end and a lower portion adjacent the lower end, the centrifuge tube further including a flexible connecting member of a predetermined length and a cap, the connecting member being attached at one end to the centrifuge tube and at the other end to the cap;
• a cylindrical filter tube of a second length less than the first length adapted to be fit in axial alignment within the upper portion of the centrifuge tube and to seal the open upper end of the centrifuge tube, the filter having an opening at its upper end;
• the filter tube including a means for positioning the filter tube in a predetermined position within the upper portion of the centrifuge tube;
• the connecting member being adapted to secure the filter tube in the predetermined position in the centrifuge tube while the cap seals the opening at the upper end of the filter tube;
• and
• means for separating a predetermined amount of a mixture of permeable and nonpermeable materials placed in the filter tube when the composite assembly is spun in a centrifuge such that the nonpermeable materials are retained in the filter tube and the permeable materials which pass through the filter means are collected in the lower portion of the centrifuge tube including, filter means disposed at the lower end of the filter tube for separating permeable materials from nonpermeable material.