Regarding Freezing Cryovials®, Let Me Share My Thoughts

The freezing technics have evolved in parallel with the lowering of the temperature of mechanical freezers or liquid nitrogen containers.

As a result, the vials themselves have also evolved in order to provide a safe environment for samples and ease of use for technicians and researchers alike. On this note, I am going to address two topics that are quite debated, try to shed some light on them, and consequently, enlighten users' choices. Since Simport® is the inventor of Cryovial®, I feel free to share my views on this!

Why is Simport® recommending that Cryovials® not be immersed in the liquid phase of nitrogen?

By the way, Simport® is by no means the only manufacturer making this recommendation. I don’t recall ever seeing a manufacturer not suggesting this. The reason is simple, if cryogenic vials are generally tight when properly used, there is no way to ensure that the cap is properly screwed on when it is deposited into the nitrogen container. The slightest screw failure will therefore allow the liquid to enter the vial. Already, this is not a great result. Liquid nitrogen in dewars is frequently contaminated with all sorts of things like Mycoplasma*. It’s uncool (no joke) to add Mycoplasma to your cells to eventually thaw and seed them to finally end up contaminating your incubators… But, in addition, there is a potential hazard. When the vial is taken out of storage, the rapid expansion of nitrogen from liquid to gaseous could theoretically turn your container into a small bomb! This is because its sealing properties would retain nitrogen passing very quickly from -196 °C to 20 °C, multiplying its volume and causing its sudden breakage. Bottle Exploding with Liquid Nitrogen Video 

Obviously, a cryogenic vial is not a soft drink bottle. Its wall is thicker among other things. I also realize that many people place their vials in the liquid phase of LN2 and have never encountered this type of problem. But the risk remains and we must warn you. In order to possibly mitigate this, please make sure to keep enough headspace (10% of the volume of the vial for example) to allow for sample expansion,(which also causes breakage) but much more to prevent large amounts of nitrogen from accumulating in the vial.

What type of cap should you choose to achieve maximum sealing?

At Simport® we made the choice not to limit ourselves to one technology but to develop them all to the top of their possibilities. We offer Cryovials® with internal threads and others with external threads. Those with internal threads were the first ones on the market. They offer excellent sealing and a choice of seals is also available. Either a white washer style that is compressed on the top of the tube (T311 series) or a round, red o-ring version that is unique to Simport® and that fits between the inner wall of the tube and the screw cap (series T301).

Then, when the market started to look at external thread tubes, because of the actual or perceived decrease in the potential for contamination, three other models were introduced. A molded lip (T309 series) simplifies the manufacturing because a washer does not need to be inserted into the cap. This model has demonstrated its excellent sealing capacity in our qualification tests. We also launched a more classic white washer model (T310 series). But to mark our domination in the cryogenics field, we developed the ultimate vial, the best Cryovial® on the market, the T308 series! Indeed this one offers a long molded inner lip and, as a bonus, an o-ring to compress. It’s the equivalent of the combination of shoulder straps and a waist belt, but for a cryogenic vial!

This is all very nice but we still need to answer the initial question; which one of these models is the best? I think it’s up to you, the customer to decide. Your sensitivity, the training you received, the type of sample you are going to freeze, and the instrument used. All this comes into play. The good news is that we are sure to have a model that fits the bill. We will gladly send you samples in order for you to try them out and decide for yourself!

*LN2 Contamination with Mycoplasma