Method and device for separating serum/plasma from blood

A device for separating serum or plasma from a given volume of blood, comprising:

• a test tube having a peripheral sidewall with an inner peripheral surface and two opposite ends;
• a separating body disposed in said test tube, said separating body including a shell having a first recess which opens axially towards one of said ends, a second recess which opens axially towards the other of said ends, an axially extending internal passage connecting said first and second recesses, and an outer periphery which is spacedly surrounded by said inner peripheral surface of said sidewall, so as to leave an annular gap therebetween;
• said separating body further including a filling of viscous or fine granular material received in said first recess;
• said separating body having a specific gravity substantially corresponding to that of leukocytes and thrombocytes contained in the blood that is to be separated;
• said filling having a higher specific gravity than said shell;
• said separating body being disposed near said one end of said test tube;
• and
• means closing both ends of said test tube and being constructed to permit a given volume of blood to be introduced into said test tube, so that, in use, a given volume of blood can be introduced into the test tube and the blood-containing test tube centrifuged in an orientation such as to separate said blood into a heavy phase containing red corpuscles and located between said one end and said separating body and a light phase containing serum or plasma and located between said opposite end and said separating body, plus leukocytes and thrombocytes located in said light phase adjacent said second recess and so that upon further centrifuging in said orientation, said filling flows axially out of said first recess and, reversing axial direction, into said annular gap thereby sealing said annular gap, creating a negative pressure in said second recess and at least some of said leukocytes and thrombocytes are sucked into said second recess, whereby light phase relatively free of leukocytes and thrombocytes remains outside said separating body in said test tube, between said separating body and said opposite end.