Vacuum blood collection tube Type: Clot activators Gel separator / Clot activator K3-EDTA Anticoagulant K2-EDTA Anticoagulant Sodium Citrate 3,8% Anticoagulant Sodium Citrate 3,2% Anticoagulant Sodium Flouride/ Potassium Oxalate Lithium Heparin Anticoagulant ESR - Sodium Citrate 3,8% Granules & Clot Activator Vacuum Tube for Urine Collection. Most blood collection tubes contain an additive that either accelerates clotting of the blood (clot activator) or prevents the blood from clotting (anticoagulant). A tube that contains a clot activator will produce a serum sample when the blood is separated by centrifugation and a tube that contains an anticoagulant will produce a plasma sample after centrifugation. Some tests require the use of serum, some require plasma, and other tests require anticoagulated whole blood.