Blood centrifugation is a lab procedure that is often performed to separate plasma from blood for the purpose of Apheresis. Satellite bags or sterile tubes are used to store the centrifuged blood. The process is done with the help of a centrifuge machine that spins the sample until all the components of blood are separated. The red cells are heavier, so they sink to the bottom of the tube, whereas the plasma sits at the top.Â
You may need to connect with a molecular bioproducts‘ supplier to purchase instruments for the transfer and storage of blood components separated through centrifugation.
Method To Separate Blood Components: Serum And Plasma
The serum is a fraction of the blood that has a liquid configuration. Once the blood starts to clot, this component can be collected from the sample. After centrifugation, the clot is eliminated from the tube and the remaining designated serum is extracted with the help of a Pasteur pipette.Â
On the other hand, plasma is generated after the whole blood is transferred into tubes treated with anticoagulants. Thus, blood clotting is prevented in plasma tubes. The cells are then spun in a centrifuge to separate plasma cells. A Pasteur pipette is then used to remove the supernatant, designated plasma, lying in the cell pellet.Â
Serum Preparation:
Store whole blood in a test tube covered with a cap. A red-topped tube should be the preferred option if commercially accessible containers are to be used. Once the whole blood is collected, store it at room temperature to allow the clotting process to begin. Let the tube sit for about 15-30 minutes before removing the clot. Spin it in a refrigerated centrifuge for 10 minutes at 1000-2000 x g for successful separation of the blood clot.
Post-Procedure Handling Instructions:
The resultant designated serum is called a supernatant. After the centrifugation process, take a propylene tube and transfer any remaining liquid (serum) from the samples into it. Use a Pasteur tube to carry out the transfer without any spills or errors. The standard temperature for the handling of a serum sample is 2-8 °C.Â
If the sample is to be stored before it is sent to the researcher for analysis, divide it into portions of 0.5ml and transfer each into an aliquot. Maintain a temperature below 20 °C for transfer and storage of the sample. A freeze-thaw cycle should be avoided so as to prevent the disfigurement of serum components. Remember that a sample that is icteric, hemolyzed or lipemic can alter test results. (Plasma and Serum Preparation, n.d.)
Plasma Preparation:
To separate plasma from blood, you have to first collect the whole blood sample into an anticoagulant tube, treated with EDTA (lavender topped) or citrate (light blue topped). For certain applications, a heparinized tube (green-topped) may also be utilized. However, this involves the risk of contaminating heparin with endotoxin. The release of this enzyme can trigger a reaction from white blood cells, resulting in the production of cytokine.Â
A 10-minute centrifugation in a refrigerated centrifuge, at 1000-2000 x g separates blood cells from plasma. Platelet depletion can occur if the centrifugation at 2000 x g extends for 15 minutes.
Post-Procedure Handling Instructions:
With the help of a Pasteur pipette, transfer plasma into a clean propylene tube. For handling, maintain a temperature of 2-8 °C, just like a serum sample. Convert it into 0.5 ml aliquots if the sample is to be analyzed later. Store and transport it at -20 °C or below. Make sure that the sample does not go through a freeze-thaw cycle to retain the validity of test results. Samples that are hemolyzed, lipemic or icteric may impact the specific tests.
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References
Plasma and Serum Preparation. (n.d.). Thermo Fisher. Retrieved May 31, 2022, from https://www.thermofisher.com/pk/en/home/references/protocols/cell-and-tissue-analysis/elisa-protocol/elisa-sample-preparation-protocols/plasma-and-serum-preparation.html
