Re: aliquoting 4% formaldehyde

Posted by Pippa Hawes on
URL: http://confocal-microscopy-list.275.s1.nabble.com/aliquoting-4-formaldehyde-tp7585663p7585681.html

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Hi Doug

 

We regularly freeze aliquots of 4% para for fixation for confocal microscopy and I’ve never seen any artefacts that can be attributed to this.  We make the aliquots up using paraformaldehyde and PBS, separate into 10ml aliquots in Universals and freeze at -20.  Once an aliquot is thawed and used, the left over is thrown away, we do not re-freeze.  The colour should be completely clear, if there is a very slight yellow tinge then polymerisation has occurred and I wouldn’t use it. 

 

I suspect there is a buffer related issue, as others have said, rather than a problem caused by freezing. 

 

Oh, and we make sure to store our fixatives (para or glut) in a different freezer to our antibodies as there will be a small amount of gas produced which will fix any protein hanging around in your freezer (fridge too, of course).

 

Good luck sorting it out!

Pippa

 

From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Cromey, Douglas W - (dcromey)
Sent: 20 September 2016 15:34
To: [hidden email]
Subject: aliquoting 4% formaldehyde

 

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I was talking with a student yesterday about their cells which did not look particularly good under the microscope. The discussion eventually came around to fixation. The student told me that he made up some 4% formaldehyde fixative and then froze back (20 deg C) aliquots for later use. This was something he had seem on an online research forum. In my fairly lengthy experience I have never heard of this being done and I am suspicious that this is NOT a good idea. Thoughts?

 

Doug

 

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