I use 50 mL falcon tubes often to freeze aliquots and stocks and today I found that 10 of them had shattered in the freezer, potentially contaminating all my aliquots of bicarbonate solution. Each tube had 40 mL of bicarbonate concentrate to give it 10 mL to expand into while freezing. I've frozen tubes like this before in the exact same freezer with the exact same solution at the exact same volume without issue but now it happened consistently 10 times. Any idea why this is happening? Anyone else having the same problem?
Hi,
I've never came across this problem. I stored my tubes even in - 80°C, and that shattering never happened to me. I think the tubes quality would make the difference. I suggest changing these tubes to bigger ones (100ml) or split your sample into two tubes (20 ml each one) in order to give the solution more space to expand. You must also read the bicarbonates behavior under freezing (Thermic tolerance).
Best of luck.
also rarely happen in our lab. Maybe batch manufacturing errors. Try using a different batch or trying buying from a different vendor/brand.
This link may help. Also, If the upper part of sample freezes hard first and limits movement, when the rest of sample freezes, it’s full pressure is on the plastic, which is likely polypropylene. Perhaps adjusting the freezing temperature might help, and avoiding the flash freezing that might limit room for expansion as the outer layer freezes hard first, limiting expansion ability as inner fluid freezes.
https://engineering.mit.edu/engage/ask-an-engineer/why-do-plastics-get-brittle-when-they-get-cold/
The manufacturer suggested the foam rack the tubes come in may be to blame because it changes how the liquid in the bottom of the tube freezes.
I once had the same problem. I think it is the foam rack that kept the bottom warmer so the top froze first and when the bottom finally reached to the temperature to freeze there is no extra room for the liquid to turn into solid which caused stress on the tube and shattered it. After that, I always use a plastic tube rack and never had a similar problem again.
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