New and improved method and apparatus for the provision of a satisfactory physical and chemical barrier at a fluid interface in the nature of that which occurs at the interface of the separated plasma and packed cells layers in centrifuged blood samples are provided, and are embodied by barrier means which are of greater specific gravity than said blood plasma layer but lesser specific gravity than said blood cells layer and are operable, upon insertion into a centrifuged blood sample container, to sink through said blood plasma layer substantially to said interface and to be wetted and expanded by said blood plasma to expand into firm contact with each other and with the walls of said container to automatically form said barrier at said interface.
A sealant for separation of a sample of blood into serum or plasma and clot portions, which has a specific gravity of about 1.03 to 1.08 and a viscosity of about 5,000 to 1,000,000 cps at a shearing speed of 1 second.sup.-1 when measured at 25.degree. C. and comprises as the essential component a polymer essentially consisting of the units of at least one of alkyl acrylates and alkyl methacrylates, and which forms a separator between the serum or plasma portion as the upper layer and the clot portion as the lower layer formed as the result of centrifugation of the blood sample so that the serum or plasma portion is readily separated from the clot portion by decantation.
The separation of a sample of blood into serum and clot portions is accomplished by means of a sealant consisting essentially of a silicone fluid and silica dispersed therein. The separation is accomplished by inserting a device containing a supply of the sealant into a container holding a sample of the blood, the device being characterized by a nozzle portion which extends into the sample. The container and device are centrifuged so that it separates into serum and clot portions and the sealant, having a specific gravity of at least 1.026, separates the two portions.
An improved blood collection container having a reduced portion disposed between its closed longitudinal ends and a stopper means disposed therein and adopted under the influence of centrifugal force to be securely received in the reduced portion is described.
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.
A blood collection and separator assembly of the type suitable for use in centrifuging blood to separate the plasma, the light phase, from the cellular portion, the heavy phase. The assembly includes a collection container and a pair of cylinders slidably disposed in the container. The first or top cylinder has a specific gravity greater than the light phase and the second or bottom cylinder has a specific gravity lighter than the heavy phase. Interposed between the cylinders are one or more layers of micro encapsulated beads of gelatin or other sealant. The average specific gravity of the first plus the second cylinders is between that of the plasma and red cells, so that the pair of cylinders float on and above the top of the heavy phase, thereby establishing the seal slightly above the interface between the light phase and heavy phase of the blood. When centrifuged the two cylinders move to the top of the packed red cells and break and squeeze out the sealant thereby forming a seal between the cylinders and the inner wall of the container slightly above the interface between the two phases of the blood.
