Why cant I submerge NALGENE or NUNC cryogenic vials in liquid nitrogen?
Actually, if you read the instructions carefully, you should not submerge any brand of cryogenic vials into liquid nitrogen. This is because of the effect the extreme cold of the liquid nitrogen has on plastics. There is significant shrinkage and embrittling of plastics at cryogenic temperatures, which makes any sealing system ineffective against liquid nitrogen. Liquid nitrogen also has a relatively low surface tension, which makes it easier to seep into the vial. So there is currently no screwtop cryogenic vial on the market today that can claim to be leakproof in liquid nitrogen. Once liquid nitrogen has gotten into the vial, there is a significant risk that the vial will explode during thawing, in addition to the potentially deleterious effects of the liquid nitrogen on the sample. That is why Nalge Nunc International offers CryoFlex Tubing, which forms a complete seal around the cryogenic vial and prevents liquid nitrogen from getting inside. We also recommend vapor-phase storage
