Heparin Blood Collection Tube Sodium Lithium Green Top Plasma Chemistry Product Overview Heparin Blood Collection Tubes are green-top anticoagulant tubes designed for rapid blood sample processing in clinical laboratory testing. Available with sodium heparin or lithium heparin , the tubes inhibit coagulation by interfering with thrombin formation and platelet aggregation, helping maintain anticoagulated blood samples for plasma-based analysis. They are commonly used for