The method of isolating serum or plasma from the formed elements of blood comprising steps of effecting precipitation of the formed blood elements to the bottom of a container, inserting a plug into the container, said plug having normally closed valve means which are openable when pressure within the container is greater than atmospheric pressure. A handle for manipulating the plug functions as a container to collect and remove serum or plasma. In a second embodiment, the handle is removably attached to the plug so that the plug can be left in place in the container to maintain isolation between the serum or plasma and the formed blood elements. In a third embodiment, the plug is provided with a container for collecting and storing the serum or plasma. A similar plug inside the container is used to effect an additional filtration step.
This invention is a continuation-in-part of my copending application, Ser. No. 58,557, filed July 7, 1970 entitled "Serum Separator and Method of Use," now U.S. Pat. No. 3,661,265.
BACKGROUND OF THE INVENTION
Ordinarily, separation of the formed elements (white cells, red cells and platelets) of blood from the serum is accomplished by the use of a centrifuge. In my copending application, Ser. No. 847,469, filed Aug. 4, 1969, there is described a method of chemically separating serum or plasma from the formed elements of blood by adding a positively charged polymer and a lectin to the blood in a collection tube.
With either method, a short time after the formed elements are precipitated, the red blood cells begin to liberate potassium and other contaminants which may interfere with the tests performed on the serum or plasma. Consequently, it is desirable to isolate the serum or plasma from the formed elements promptly after mechanical or chemical precipitation. With chemical separation methods, small amounts of red cells and fibrin may be left in suspension, and it therefore it also desirable in the case of chemical separation to remove all of the residual suspended matter from the serum or plasma.
In the past, attempts have been made to isolate centrifugally separated serum from the formed elements by the use of a pick-up device consisting of a first tube fitted at the lower end with a rubber element adapted to engage and slide along the walls of a collection tube. The pick-up device has a second tube which passes through an opening in the rubber element to a point near the upper end of the first tube, and the second tube has a downwardly facing opening which delivers serum into the first tube as the pick-up device is pushed into the collection tube. The device is inserted into the collection tube, fills with serum, and is then removed from the collection tube. The serum retained in the device can then be tested.
A problem with the use of the device just described is that it cannot be used to transport the separated serum or plasma to the laboratory for testing from the point at which the blood sample is taken. Consequently, the collected serum must be transferred to a suitable container in a time consuming and error prone procedure. This problem becomes serious where blood tests are being performed for a large number of persons.
If the pick-up device just described were used in conjunction with a chemical separation method where the presence of suspended debris in the serum or plasma is likely, the debris would pass into the first tube of the pick-up device through the second tube.
SUMMARY OF THE INVENTION
In accordance with this invention, the serum separator includes a plug consisting of a disc having one way valve openings associated with a fibrous filter disc which prevents suspended debris and formed elements from passing through the plug. The plug thus maintains the separated serum or plasma relatively free of contaminants.
In accordance with a first embodiment of the invention, there is provided a separation device which, itself, may be used for transporting serum or plasma to the laboratory for testing.
In accordance with a second embodiment of the invention, a separation plug is left in the blood collection tube, and maintains the formed elements and the serum or plasma isolated from each other. In this case, the collection tube itself can be used for transporting the serum or plasma to the laboratory.
In accordance with a third embodiment of the invention, a separation plug is provided with a container for collecting serum or plasma. The container has its own internal separation plug similar to the one to which it is attached. The internal separation plug is used to effect a second filtration prior to testing of the serum or plasma.
An improved method for isolating a liquid sample from a specimen container employing an elongated cylindrical tube, sized for insertion into the specimen container, and having a hollow neck formed at one end of the tube. A thin, flexible circular disc projects from the neck for slidable sealing engagement with the internal cylindrical wall of the specimen container. A shoulder is formed on the neck adjacent to the circular disc for engaging and supporting at least a portion of the disc to maintain the seal during insertion and release it during withdrawal of the tube. A removable sample measuring cup on the other end of the tube provides control of an air vent in the tube and instantaneous and easy transfer of the collected sample. The container also desirably includes a filter disposed in said neck aperture to limit the fluid flow from the tube.
Method and apparatus for filtering and permanently separating the serum fraction from the cell fraction of centrifuged blood and the like. A separator head is passed through the serum and is positioned at the interface of the serum and the heavier red cells. As the separator head is positioned serum passes through a self-sealing passage in the separator head and into a collection tube that positions the separator head. Upon withdrawal of the collection tube the passage in the separator head closes sufficiently to effectively block the passage and the serum can be poured from the collection tube. The collection tube can be reinserted to pour off measured volumes of the serum.
A filter skimming device comprising an elongated plunger assembly adapted for telescopic insertion in a test tube. The plunger assembly has an elongated plunger tube, a filter element, an elongated tubular insert for collection of filtered fluid, and a molded-in channel in said tubular insert for carrying said filtered fluid from said filter to the interior of said insert.
A method and apparatus for separation and filtration of particulate matter of sediment from a liquid sample. The system includes a unitary filter assembly having an intermediate fibrous filter material disposed between two layers of porous, relatively rigid plastic material. The unitary filter assembly is pressed axially toward the closed end of a sample container, such as a test tube, resulting in an upward flow of filtrate with compaction and retention of the particulates between the unitary filter assembly and the closed end of the sample container. The filter assembly is free of orientation criticality and may be readily adapted to automated handling in multiple tests or assays.
The present invention provides a method and device for detecting the presence of binding ligands, especially blood group antigens or antibodies thereto, which utilize a matrix of substantially noncompressable microparticles, which matrix provides superior performance in allowing movement of nonagglutinated reactants, especially red blood cells, while constraining, preferably in a so-called "band formation" agglutinated reactants, especially red blood cells.
