Storing samples at low temperatures is associated with extended viability of the preserved samples. While many samples are stored in mechanical freezers at -80°C, it is important to note that at this temperature metabolic activity has not ceased, it has only slowed down. By reducing sample temperatures to below the glass transition phase of water (-132°C), all metabolic activity comes to a halt. Sample storage below this temperature - in vapor phase LN2 - therefore assures a safe form of preservation.
The temperature range of the material of the Micronic tubes, racks and caps is approved from -80ºC to +100ºC. In practice Micronic products are used in cryogenic temperatures until vapor phase LN2. Vapor phase LN2 temperatures range between -150°C and -196°C, depending on the location and the distance away from the liquid nitrogen vessel.
Micronic does not recommend to store samples in liquid phase nitrogen, as there are several risks associated with storing samples in these kind of storage systems:
Micronic therefore recommends to only snap freeze sample storage tubes in LN2 without submerging the cap.