Tubes containing 0.5 ml of CTAD anticoagulant specially prepared by Esoterix Coagulation are available from MLabs. Collection instructions: Perform the venipuncture using a butterfly needle set and a two-syringe technique. Discard the first syringe after 2 ml of blood have been collected, then collect 5 ml of blood in the second syringe. Gently express 4.5 ml of blood from the syringe gently down the side of the CTAD tube. Cap and invert gently three times and place on ice for at least 15 minutes. Centrifuge tube at 2500 g for 30 minutes in a refrigerated centrifuge within 1 hour of collection. Aliquot one-third of the plasma from the middle region of the plasma portion into a plastic vial and freeze at -70 degrees. Transport frozen on dry ice.