[Histonet] Warm up freezer-stored powder, or use right away?

[Morken, Timothy]

Here is the answer I got from Sigma-Aldrich Tech Support. 

" We would not recommend bringing the entire bottle up to room temperature to weigh.  Repeated freeze/thaw cycles can degrade the product. If you are worried about ice crystals affecting weight, you can bring a small sample up to room temp before weighing, or weigh out directly from the cold bottle and reweigh after equilibration."



Tim Morken
Pathology Site Manager, Parnassus 
Supervisor, Electron Microscopy/Neuromuscular Special Studies
Department of Pathology
UC San Francisco Medical Center

-----Original Message-----
From: Bob Richmond via Histonet [mailto:histonet at lists.utsouthwestern.edu] 
Sent: Friday, May 25, 2018 10:48 AM
To: Histonet at lists.utsouthwestern.edu
Subject: Re: [Histonet] Warm up freezer-stored powder, or use right away?

Tim Morken (Pathology Site Manager, Parnassus - Supervisor, Electron
Microscopy/Neuromuscular Special Studies Department of Pathology - UC San
Francisco Medical Center) asks:

>>We have a debate going on for those freezer-stored powdered chemicals
used for enzyme histochemistry. One side says warm up the container to room
temperature before opening in order to prevent water condensation in the
container/powder. The other side says to use right away and put back in the
freezer to avoid long exposure at room temperature. I'd like to hear pros
and cons of each and any references stating one practice or the other.<<

Opening that freezer-cold bottle before it warms up is ruinous. What I was
taught to do in a research histochemistry lab (yeeks, this is a little less
than 50 years ago) is to weigh out the needed quantity of the chemical
(say, 10 mg of ATP) into empty gelatin capsules, and put the filled
capsules in the freezer. When you do the procedure, take a single capsule
out of the freezer. You could make up big batches of these capsules on a
slow day.

Bob Richmond
Samurai Pathologist
Knoxville TN
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