Opening the eternal debate. For long-term storage of lyophilised material I keep everything at −80 °C and I will not apologise. Colder = slower degradation, full stop.
I know MinusTwentyMo is going to tell me a normal −20 freezer is fine for shorter windows and that not everyone has a −80. Fair. But "fine for now" and "best for stability" are different claims. Let's hash it out and maybe land somewhere useful for the newcomers reading.
On cue. I'm not arguing −80 is worse — it's better for long-term, obviously. I'm arguing that for lyophilised material over a normal use window, a reliable −20 is perfectly serviceable and most people don't own a −80. "Best" and "sufficient" are different words.
The stability data I've read supports both of you, annoyingly. Colder slows degradation (Fiona) AND lyophilised powder is robust enough that −20 is fine for typical windows (Mo). The real enemy is freeze-thaw cycling, not the exact setpoint.
Shay naming freeze-thaw as the real villain is the point I keep failing to make gracefully. Fine: −80 for long-term archival, −20 acceptable for active short-term, and for the love of stability stop cycling your vials in and out.
I'll take that treaty. Aliquot so you only thaw what you need, store the rest cold and undisturbed, go colder if you've got it for the long haul. We agree, Fiona. Don't make it weird.
Marking the consensus for the newcomers: minimise freeze-thaw via aliquoting, −20 acceptable for active stock, −80 preferred for long-term, lyophilised is the most forgiving form. Excellent thread.
New evidence from the Freezer Tetris thread: my −80 may be a landslide hazard, but it is a COLD landslide hazard. The science holds even when the shelving does not.
"Cold landslide" is going on a label immediately. Truce still holds, Fiona. Aliquot, minimise freeze-thaw, store cold, stop arguing. We did it. We're role models now, somehow.
Months on and the "freeze-thaw is the real villain" consensus has quietly saved more stock than the setpoint argument ever could. Best treaty on the forum.
Marking the consensus for newcomers landing here: minimise freeze-thaw via aliquoting, −20 is fine for active short-term stock, −80 for long-term archival. Lovely thread, and a model for how to disagree well.
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