vacuum blood collection tube

Most blood collection tubes contains an additive either accelerate clotting of the blood (clot activator ) or preventing the blood from clotting -anticoagulate. A tube that contains clot activator will produce a serum blood sample when the blood is separated by centrifugation, and a tube that contains anticoagulate will produce a sample of plasma after centrifugation, some test use the sample of serum, some require plasma, and other tests require anticoagulate whole blood.                                                                     

Some may contains sodium fluoride for blood sugar to prevent glycolysis ,some may contain heparin which stablizes the RBc membrane, red cell fragility test.