Serum and Plasma Preparation

Q-Plex™ kits are often developed with serum or plasma samples as the primary sample type. Here are some recommended procedures for the collection, processing, and shipment of serum and plasma samples. Serum is the liquid fraction of whole blood that is collected after the blood is allowed to clot. The clot is removed by centrifugation and the resulting supernatant, designated serum, is carefully removed. Meanwhile, plasma is produced when whole blood is collected in tubes that are treated with an anticoagulant. The blood does not clot in the plasma tube. The cells are removed by centrifugation. The supernatant, designated plasma is carefully removed from the cell pellet using a pipette.

Serum Preparation

Collect whole blood in a covered test tube. After collection of the whole blood, allow the blood to clot by leaving it undisturbed at room temperature. This usually takes 30 minutes and no more than one hour. Remove the clot by centrifuging at 1,000-2,000 x g for 10 minutes. The resulting supernatant is designated serum. Following centrifugation, it is important to immediately transfer the liquid component (serum) into a clean polypropylene tube using a pipette. The samples should be maintained at 2-8°C while handling. If the serum is not analyzed immediately, the serum should be aliquoted, stored, and transported at -20°C or lower. It is important to avoid or at least minimize freeze-thaw cycles because this is detrimental to many serum components. Samples which are hemolyzed, icteric or lipemic can invalidate certain tests.

Plasma Preparation

Collect whole blood into tubes with the anticoagulant EDTA. Cells are removed from plasma by centrifugation for 10 minutes at 1,000-2,000 x g. Centrifugation for 15 minutes at 2,000 x g depletes platelets in the plasma sample. The resulting supernatant is designated plasma. Following centrifugation, it is important to immediately transfer the plasma into a clean polypropylene tube using a pipette. The samples should be maintained at 2-8°C while handling. If the plasma is not analyzed immediately, the plasma should be apportioned into aliquots, stored, and transported at –20°C or lower. It is important to avoid and/or minimize freeze-thaw cycles. Samples which are hemolyzed, icteric, or lipemic can invalidate certain tests.

References

• Henry, J.B. (1979) Clinical Diagnosis and Management by Laboratory Methods, Volume 1, W.B Saunders Company, Philadelphia, PA, p. 60.
• Thavasu, P.W., et al (1992) Measuring cytokine levels in blood. Importance of anticoagulants, processing, and storage conditions. J Immunol Methods 153:115-124.