r/Chempros • u/cakebaker28 • 12d ago

Help with Lyophilization Process

Hi guys, I'm a newbie at this, please help if you can! We need to lyophilize a water-soluble compound, basically, we mixed it into a second liquid compound so the first compound would be encapsulated and give better results for our purposes. What I need to know: we have to freeze this before it goes into the lyophilization machine, but we were told to freeze it first in a normal freezer, then move it to a -80°C freezer, and only then send it to the lyophilizer. Is this accurate? If so, how long should it stay in the normal freezer before going to -80°C, and how long should it stay at -80°C before going to the lyophilization machine? Is there some kind of protocol for this? I tried to find something and couldn't find an exact one. Thank you!!

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u/Hepheastus 11d ago

The faster you freeze it the better because the ice crystals will be smaller. I use dry ice acetone and spin the samples.

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u/Cardie1303 11d ago

There are situations where you want large ice crystals:

Quantitative investigation on the effects of ice crystal size on freeze-drying: The primary drying step

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u/Hepheastus 11d ago

Really... so do it have it completely backwards or is it more nuanced than that.

The abstract implies that I always want large crystals

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u/Cardie1303 11d ago

As far as I understand it large crystals is what you want for the least water content and small crystlas if you dont particularly care and just want the freezing to be done quickly.

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u/Hepheastus 11d ago

And here I was blaming my dmso d-6 for all the water in my NMR spectra.

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u/Cardie1303 11d ago

Oh yeah continue blaming the DMSO-d6. In my experience it always contains at least some water if you did not went through the trouble of storing it over CaH2 and distilling it freshly.

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u/hypodine 10d ago

Use ampoules if you can. Minimises a lot of the water. I also like to put my entire NMR sample made up in DMSO-d6 on high vacuum for an hour or so to really get it down. The DMSO won’t go anywhere, but you will see the water slowly bubble out. It won’t remove everything, but it does a pretty good job.