Plasma and Serum

PLASMA AND SERUM

  • Blood consists of plasma in which erythrocytes, leucocytes and thrombocytes (platelets) are suspended.
  • Plasma, in turn consists of serum and fibrinogen.
  • Action of thrombin on fibrinogen separates out fibrin.
  • Serum is rich in albumin and globulin.
  • Thus, plasma is recovered from unclotted blood by centrifugation, whereas serum is obtained from clotted blood.
  • It may be noted that normal blood clotting time of most domestic animals is 3 to 6 minutes.
  • Only from those abattoirs where slaughter is carried out on bleeding rails blood can be collected for human use.
  • Trocar knife (with hollow handle) and canula are used for hygienic recovery of blood, which is collected in clean and sterile stainless containers.
  • An ideal vessel should have a diameter of 45 cm and a depth of 15 cm.
  • It can be washed with hypochlorite or steam sterilized.
  • To prepare plasma
    • blood collection is done quickly in an anticoagulant (trisodium citrate 4%, 1 ml for each 10 ml of blood, otherwise oxalate, EDTA or heparin is used).
    • Blood is then centrifuged, which will separate plasma from cell mass.
    • Plasma is stored in bottles or polyethylene bags in frozen conditions.
  • To prepare serum
    • blood is collected carefully and allowed to clot and subjected to further processing in a cold room.
    • Chilled clotted blood is cut into smaller lumps to bring about quick contraction of clots.
    • Serum collected in first 12 hours is generally clear except for some suspended RBCs.
    • It is centrifuged in a bucket centrifuge at 100 rpm and filtered through Seitz filter.
    • The yield of serum is about 10-12% of the weight of whole blood.
    • It keeps well at 4-5oC for one month and at –20oC for six months.
    • Dried blood serum is referred as blood albumen and is used as the cheapest substitute for dried egg albumen powder in the industry.
      • To prepare it, to clear yellow serum is added 0.05% phenol on weight basis.
      • It is sprayed or vacuum dried to soluble fine powder.
      • The yield of albumen is 10-20% of the weight of the serum.
      • It is stable in airtight containers in cool places for several months.
Last modified: Thursday, 16 September 2010, 6:23 AM