Norgen's cf-DNA/cf-RNA Preservative Tubes Dx are closed, evacuated plastic tubes for the collection and the preservation of cf-DNA, circulating tumor DNA, cf-RNA and circulating tumor cells in human whole blood samples during storage and shipping. Using these tubes in combination with Norgen's Plasma/Serum Cell-Free Circulating DNA Purification Kits or Norgen's Plasma/Serum RNA Purification Kits enables the purification and concentration of an inhibitor-free cf-DNA/ct-DNA/cf-RNA in a very small elution volume.nnThese tubes are ideal for collecting and preserving cf-DNA and cf-RNA samples for in vitro diagnostic use for medical purposes.