Yes, you may see some pink colouration to the plasma. The Cell3 Preserver tubes contain stabilisation additives which protect and prevent white blood cells from breaking apart. Keeping the white blood cells intact prevents genomic DNA contamination in the plasma sample. However, red blood cells have thinner walls and may break down in a process called haemolysis. Red blood cells do not contain DNA and therefore will not contribute to any genomic DNA contamination in the plasma sample.