[3dem] Precipitation observed after making freeze substitution cocktail containing 5% water

[Gibson, Kimberley]

It's not possible to make a stock solution of 20% Uranyl Acetate. Even making a 10% UA stock is not possible. At best, the solubility of UA is around 7-8 % in water. It's best to make a 5% stock solution, dissolved in water, for example, and add the quantity of 5%UA to the acetone. The precipitation of UA is likely due to the acetone as UA is not really soluble in acetone.
Best,

Kimberley Gibson

Research Associate, Charles Sindelar Lab

Dept. Molecular Biophysics and Biochemistry
Yale University
________________________________
From: 3dem <3dem-bounces at ncmir.ucsd.edu> on behalf of Christopher Peddie <Christopher.Peddie at crick.ac.uk>
Sent: Thursday, December 19, 2019 03:56
To: Qiaohui Yang <qiaohui.yang at ymail.com>
Cc: 3dem at ncmir.ucsd.edu <3dem at ncmir.ucsd.edu>
Subject: Re: [3dem] Precipitation observed after making freeze substitution cocktail containing 5% water


Hi Qiaohui,



Mix the osmium, water and acetone and cool to -20oC. Then add the uranyl acetate from a stock e.g. 20%. Cooling the mixture in my experience stops the uranyl acetate from precipitating out.



Best,

Chris





From: 3dem [mailto:3dem-bounces at ncmir.ucsd.edu] On Behalf Of Qiaohui Yang
Sent: 19 December 2019 08:39
To:
Subject: [3dem] Precipitation observed after making freeze substitution cocktail containing 5% water



Hi everyone!

We recently tried to make freeze substitution cocktail consisting of 1% osmium tetroxide, 0.1% uranyl acetate and 5% water but observed that the mixture turned slightly cloudy within 1-2 minutes. We tried to see if the precipitation would occur in the absence of osmium tetroxide, and we observed some cloudiness too after mixing uranyl acetate solution in water with pure acetone.

Just wondering if anyone has encountered similar problem and if so, would appreciate some tips on how to overcome this problem.

Thank you!



Best regards,

Qiaohui



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