Method for Separating a Sample into Density Specific Fractions

Abstract

The centrifugation vessel includes an outer wall containing an interior space. A dam defines a barrier which divides the interior space into at least two regions including a catch basin defining a higher gee region and a reservoir defining a lower gee region. These regions are joined together over the dam. The dam includes a face which is preferably tapered to enable optimization of speed of separation of a sample placed within the vessel. The vessel is usable in a biological sample processing method by having the higher gee region of the vessel configured to have an elongate form and the volume optimized for collection of a higher density fraction of the sample. Supply and withdrawal tubes extend into the regions for reliable extraction and separate collection of differing density fractions after separation by centrifugation.

1 - 20 . (canceled) 
     
     
         21 . A method for separation of a sample into at least two fractions of different densities, the method including the steps of:
 identifying a centrifuge vessel having:
 an upper end and a floor end; 
 an outer wall surrounding a fluid containing interior space of the vessel, the outer wall extending from the upper end to the floor end; 
 a barrier inside the outer wall, the barrier partially dividing the interior space into at least a first region and a second region, the barrier having a lip with the first region and the second region connected above the lip and the first region and the second region spaced apart below the lip, wherein the barrier in the first region extends tapering diagonally from the lip to the inner surface of the outer wall at a position between the upper end and the floor end; 
   placing a sample into the interior space of the vessel;   positioning the vessel into a centrifuge;   spinning the vessel within the centrifuge to separate the sample into differing density fractions; and   stopping said spinning step while keeping the separated differing density fractions at least partially divided by the barrier into the first region and the second region within the centrifuge vessel.   
     
     
         22 . The method of  claim 21 , wherein said identifying a centrifuge vessel step includes locating the lip of the barrier between a higher gee side and a lower gee side of the vessel at a particular fixed position at least partially correlated with expected prevalence of the at least two fractions of the sample. 
     
     
         23 . The method of  claim 21 , wherein said identifying a centrifuge vessel step includes the region adjacent a higher gee side of the vessel having a volume below the lip of the barrier greater than an amount of a higher density one of the at least two fractions of the sample, such that the higher density fraction is collected within the higher gee region after centrifugation. 
     
     
         24 . The method of  claim 21 , wherein said positioning step includes a cradle having an upper end which is open and into which the centrifuge vessel is adapted to be removably placed along a cradle center line, the center line of the cradle oriented substantially parallel with the spin axis. 
     
     
         25 . The method of  claim 24 , wherein said identifying a centrifuge vessel step includes the barrier extending down from the lip on a side of the barrier closest to the spin axis after said positioning step, having a face extending at an angle tapering toward the spin axis as the face extends away from the lip. 
     
     
         26 . The method of  claim 25 , wherein said identifying a centrifuge vessel step includes the face tapering in a curving manner away from the lip and partially toward the spin axis as the face extends away from the lip. 
     
     
         27 . The method of  claim 21 , wherein said positioning step includes a cradle having an open upper end into which the centrifuge vessel is adapted to be placed along a center line of the cradle, the center line of the cradle angled non-parallel to the spin axis with the open upper end of the cradle located closer to the spin axis than other portions of the cradle. 
     
     
         28 . The method of  claim 27 , wherein said identifying a centrifuge vessel step includes the barrier having a face extending down from the lip on a side of the barrier closest to the spin axis, the face angled to be closer to the spin axis where the face is spaced from the lip than a distance from the face to the spin axis where the face is adjacent the lip. 
     
     
         29 . The method of  claim 28 , wherein said identifying a centrifuge vessel step includes a side of the barrier opposite the face oriented substantially parallel with portions of the outer wall most distant from the spin axis for at least a portion of the barrier after said positioning step. 
     
     
         30 . The method of  claim 29 , wherein said identifying a centrifuge vessel step includes portions of a side of the barrier opposite the face tapering at an angle relative to portions of the outer wall of the vessel most distant from the spin axis after said positioning step, the angle causing tapering portions of the wall of the barrier opposite the face to be most distant from the spin axis at a location most distant from the lip of the barrier. 
     
     
         31 . A method for processing a biological sample having at least two fractions of different densities, the method including the steps of:
 identifying a centrifuge with a spin axis and at least one sample vessel support spaced from the spin axis and adapted to spin about the spin axis;   identifying a vessel for the biological sample, the vessel sized and shaped to be supported at least partially by the sample vessel support of the centrifuge;   wherein said identifying a vessel step includes the vessel having:
 an upper end and a floor end; 
 an outer wall adapted to contain fluids therein, the outer wall extending from the upper end to the floor end; 
 a barrier inside the outer wall, the barrier dividing an interior of the container into at least a first region and a second region, a lip defining an upper end of the barrier where the first region and second region join together, and a pair of surfaces on the barrier extending down from the lip, wherein one of the surfaces extends tapering diagonally from the lip to the inner surface of the outer wall at a position between the upper end and the floor end; 
   placing a sample into the vessel;   locating the vessel into the vessel support of the centrifuge;   spinning the vessel to separate the sample into fractions; and   stopping said spinning step while keeping the separated fractions at least partially divided by the barrier into the separate regions within the centrifuge vessel.   
     
     
         32 . The method of  claim 31 , wherein said positioning step includes configuring the sample vessel support of the centrifuge as a cradle sized and shaped to have a portion of the sample vessel placed therein, and placing the vessel into the cradle. 
     
     
         33 . The method of  claim 31 , wherein said identifying a vessel step includes providing the barrier in a fixed position with a face extending down from the lip on a side of the barrier closest to the spin axis after said locating step, the face tapering toward said spin axis at least partially as the face extends away from the lip. 
     
     
         34 . The method of  claim 33 , wherein said identifying a vessel step includes the face of the barrier being substantially flat. 
     
     
         35 . The method of  claim 33 , wherein said identifying a vessel step includes the face having a concave contour. 
     
     
         36 . The method of  claim 33 , wherein said identifying a vessel step includes the barrier having a wall on a side of the barrier opposite the face which is oriented substantially parallel with a high gee side of the vessel for at least portions of the wall of the barrier opposite the face. 
     
     
         37 . The method of  claim 36 , wherein said identifying a vessel step includes portions of the wall on the side of the barrier opposite the face which are spaced from the lip exhibiting a taper away from the outer wall defining the high gee side of the vessel, the taper at an angle causing portions of the wall having the taper to angle away from the high gee side of the outer wall and away from the spin axis of the centrifuge as the taper extends from the lip. 
     
     
         38 . The method of  claim 31 , wherein said identifying a vessel step includes the barrier dividing the vessel into a reservoir on a lower gee side of the barrier and a catch basin on a higher gee side of the vessel after said locating step, a withdrawal tube extending down into the catch basin; and withdrawing high density fractions of the biological sample through the withdrawal tube after said stopping step. 
     
     
         39 . The method of  claim 38 , wherein said identifying a vessel step includes the withdrawal tube extending to a location within the catch basin most distant from the lip, the catch basin sized to have a volume such that a majority of contents of the catch basin are a higher density fraction of the sample, with the higher density fractions of the sample collecting within a lower half of the catch basin. 
     
     
         40 . The method of  claim 39 , wherein said biological sample includes fractions of at least three different densities with a volume of the catch basin sized large enough to contain the two higher density fractions; and first removing a highest density fraction from the catch basin through the withdrawal tube, and finally collecting a medium density fraction from the catch basin by withdrawal from the withdrawal tube. 
     
     
         41 . The method of  claim 31 , wherein the barrier in the second region extends from the lip to the floor end of the vessel. 
     
     
         42 . The method of  claim 31 , wherein said first region and second region have different widths.