Storage Tube Protection

Nunc Biobanking and Cell Culture Cryogenic Tubes are normally placed in a 4 degrees C ice bath during cell inoculation in the cryogenic tube. The heat required to shrink the polyethylene Nunc CryoFlex Tube Wrap will not raise the internal temperature enough to damage the cells. At this stage, cryoprotective agents are added.

We recommend the following protocol for thawing cells immersed in liquid nitrogen without Nunc CryoFlex Tube Wrap:
- Wear appropriate protective clothing including gloves, face guard, etc., during all transfer processes.
- The Nunc Biobanking and Cell Culture Cryogenic Tubes should be stored at least 24 hr in the gas phase of the liquid nitrogen freezer. This should allow trapped liquid nitrogen to evaporate and escape slowly, thereby reducing the possible pressure in the cryogenic tube.
- After at least 24 hr storage in the gas phase, the cryogenic tube may be put into a water bath and covered with a towel.
- After thawing, the contents of the cryogenic tube can be transferred.

Of the Nunc Biobanking and Cell Culture Cryogenic Tubes, we recommend the internally threaded design, incorporating a silicon gasket, for liquid nitrogen immersion. At ultra low temperatures, any sealing material becomes inflexible. A theoretical risk of leakage is present when any mechanical closure is used. To facilitate leakproof storage, mechanically closed containers must be hermetically sealed in a protective envelope.

The Nunc cryo products includes Nunc CryoFlex Tube Wrap, a heat sealable polyethylene tubing designed for cryogenic tube encasement. The use of cryogenic tubes for freezing in liquid nitrogen (liquid phase) storage without CryoFlex tubing poses a safety hazard.
WARNING: Do not use Nunc Biobanking and Cell Culture Cryogenic Tubes in liquid phase of liquid nitrogen unless correctly sealed in Nunc CryoFlex Tube Wrap (Cat. No. 343958). Improper use may cause entrapment of liquefied nitrogen inside the vial and lead to pressure build-up, resulting in possible explosion or biohazard release. Use appropriate safety procedures as outlined in the Nalge Nunc International Cryopreservation Manual when handling and disposing of the vials.