What is wet ice? - (Jan/22/2008 )

Hello,

This is such a dumb question, but exactly how does one make "wet ice"? As in, to thaw and aliquote chemically competent cells?

Is it ethanol and dry ice? How much of each?

Thanks.

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Wet ice, is your average ice from the ice machine- i.e frozen water (around 0C), which you need if you going to thaw out competent cells, dry ice will just keep them frozen (around -20C).


I wouldn't recommend adding ethanol to dry ice.

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If you mix water with your crushed ice, the competent cells (or other temperature sensitive chemicals) will thaw much more rapidly because the thermal conductivity of the water in contact with the tube is much higher.

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Dry ice/ethanol used to used before good -80C freezers were readily available.

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well you learn something everyday! Still if you want to thaw your cells and aliquot them, you probably don't want to use that....

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Dry ice/ethanol is still useful even with -80 freezers, since the thermal conductivity of the liquid is very high, and results in a flash freeze of the tubes, rather than a slow freeze. This can be important for some biological samples. Besides, it looks as if you're doing Science when you use it.

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Thaw and aliquot cells on wet ice. Freeze in a dry ice/ethanol mix and store -80. I usually use a few small chunks of dry ice and about 200-300mLs ethanol. Depends on the container you're using but if your mix becomes viscous then there is too much dry ice. You can save the ethanol (label appropriately) and reuse it the next time you want to freeze cells down.

Gotta love the drama when you're working with bubbling foggy mixes

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wet ice:
ice (of water), cooling with 0°C; to make clear that dry ice (CO2; -78°C) is not meant

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Thank you so much for all of your helpful advice!!! I very much appreciate your expertise!

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here in our lab, we add water into crashed ice and called it "ice bath"

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