1 mL serum from a plain red top tube. Allow sample to clot in an upright position for at least 60 minutes, then centrifuge sample and transfer serum to a plastic transport tube within 2 hours of collection. Refrigerate.
1 mL EDTA (lavender top) or sodium heparin (green top) plasma. Centrifuge sample and separate plasma from cells within 2 hours of collection. Transfer plasma to a plastic transport tube. Refrigerate.