Blood Fractionation

Blood fractionation is the process of fractionating whole blood, or separating it into its component parts. This is typically done by centrifuging the blood.

The resulting components are:

• a clear solution of blood plasma in the upper phase (which can be separated into its own fractions, see Blood plasma fractionation),
• the buffy coat, which is a thin layer of leukocytes (white blood cells) mixed with platelets in the middle, and
• erythrocytes (red blood cells) at the bottom of the centrifuge tube.

Serum separation tubes (SSTs) are tubes used in phlebotomy containing a silicone gel; when centrifuged the silicone gel forms a layer on top of the buffy coat, allowing the blood plasma to be removed more effectively for testing and related purposes.