Do not use alcohol or other volatile disinfectants at the site of venipuncture. Aqueous Zephiran (benzalkonium chloride), aqueous Merthiolate (thimerosal), or povidone-iodine may be used.
Do not open the tube.
Allow specimen to completely clot (this can take up to 60 minutes). Centrifuge for 15 minutes as soon as the specimen is clotted.