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Author: Subject: DIY: Freeze drying?
Biomaterialist
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[*] posted on 28-6-2011 at 01:47
DIY: Freeze drying?


Hi!

I am wondering if anybody has some suggestions on how to do a DIY freeze drying process. I have a strong pump which I use to vacuum dry reagents and products and I also have access to nitrogen, but have no clue how to do some lyophilization shenanigans.

Any comments are highly appreciated!

Other info: I want to freeze dry around 50 mL total of water from some peptides and cellulose like materials that are sensitive to high heat (in case any wonders why i do not use rotatory evaporation).
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The WiZard is In
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[*] posted on 28-6-2011 at 05:31


Quote: Originally posted by Biomaterialist  
Hi!
I am wondering if anybody has some suggestions on how to do a DIY freeze drying process.


Id The Analogue Guy shelves —

Rolland O Hower
Freeze-Drying Biological Specimens: A Laboratory Manual
Smithsonian Institution Press
1979
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Saerynide
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[*] posted on 28-6-2011 at 05:41


Hook up the vacuum pump to a cold trap (LN2 or some kind of freezer) to the thing you want to freeze dry. If using LN2, be sure no air gets in, or O2 will condense in your trap :o To be extra careful, no freeze drying of organic solvents!!!

We were about to do this in our lab when our freeze drier broke down, but I kind of chickened out (I don't want to see any pretty blue liquid :P)

I think in theory, you should be able to freeze dry without the trap, provided you have a powerful enough pump and dont mind all the water vapor going through the pump... but I didn't manage to get it to work - I guess I couldnt pull a hard enough vacuum fast enough?

Make sure you freeze the living crap out of your sample (-80 is ok, -196 is better :D). If it melts and the vacuum breaks, you're screwed and your sample will be all over the place :( happened to me too many times....

[Edited on 6/28/2011 by Saerynide]




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franklyn
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[*] posted on 29-6-2011 at 20:29


If time is not important such that you don't need the processed item yesterday
a normal frost free refrigerator freezer will dry out an item over a period of a
month or so. I did this with a pealed potato and when I removed it from the
ice box it had been lightened significantly and resembled high density foam.
I still have it outside on top of the refrigerator after 3 years and it has not
changed at all in appearance.

.
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Saerynide
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[*] posted on 30-6-2011 at 10:00


WOW.... now putting food in the freeze drier is something I've never tried (my lab would freak if they found vegetables in there lol) Did you taste it? Freeze dried icecream, pizza, and strawberries all taste like styrofoam to me :P



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chemoleo
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[*] posted on 30-6-2011 at 18:51


Peptides, proteins, biomaterials and such things are usually freeze dried by first freezing the aqueous sample (i.e. <50% volatile solvent, such as acetonitrile) in N2(l). Then it is placed into a vacuum flask, and attached through a manifold to the electric cold trap (which cools to -110C when it contains common solvents, or -50C if only H2O). A high vacuum is applied (0.1 hPa), and two days later a 20 mL sample will be freeze dried to a powdery residue.... surface area of course matters here.
You can buy cold traps, but they are worth $8 k or so. Depending on the make.
Good luck!




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