1 mL EDTA (lavender top) or sodium or lithium heparin (green top) plasma. Centrifuge sample and separate plasma from cells within 1 hour of collection. Transfer plasma to a plastic transport tube. Clearly label tube as EDTA or heparin plasma. Freeze. Critical Frozen (CFZ). patient should be fasting for 12 hours and not have ingested any alcohol for 1 day prior to collection. When multiple tests are ordered, submit separate tube for this test.