Plasma is the liquid part of the blood in which the blood cells are suspended. Plasma makes up half of the blood volume. Blood plasma has primarily a transport role. It transports blood cells and hormones throughout the body.

Plasma is extracted from whole blood by centrifugation. During the centrifugation process, the blood cells end up at the bottom of the tube and the yellowish liquid that remains is the plasma. More than 90% of plasma is water. Other components of plasma are mineral solutes such as trace elements and ions, respiratory gases (O2 and CO2) and organic solutes such as plasma proteins.

EDTA is an anticoagulant. The difference between K2EDTA and K3EDTA is that K3 is a liquid solution in the tubes, whereas K2 is a liquid solution that is sprayed as a coating on the tubes