[3dem] Ice contamination

[Bob Grassucci]

Hi Liz,
It is tough to tell from the image you sent.  What is the scale?  Is it 
the really thick ice at the top or the small round ones like in the 
lower left part of the image?  If it is the lower left round guys I 
would say it is impurities in the Ethane that is the problem.  If the 
tank was not cleaned out before refilling it or if it has been shaken or 
is close to being empty you may be getting oils etc.  from the bottom of 
the tank.  You can send me a bigger version of the image off list if you 
like.  I'd be happy to give it a shot.
Bob
On 9/27/2011 4:38 PM, Wright, Elizabeth R. wrote:
> Dear 3D EM friends,
>
> We are experiencing a problem with ice contamination within the ice of 
> our plunge-frozen samples (frozen with an FEI Vitrobot). We have 
> purchased new hoses, regulators, ethane (99.999% pure) and liquid 
> nitrogen tanks, attempted chloroform or methanol treatment of the 
> grids, glow discharged the grids with different units, and still seem 
> to be unable to remove this contaminant. It is not specimen dependent 
> as we use different buffering systems for the samples. It is also not 
> microscope dependent, we have seen it when using a variety of instruments.
>
> Has anyone observed this before (image below)? Has anyone found a way 
> to remove it? Any thoughts or suggestions would be greatly 
> appreciated. If the image does not come through, please let me know.
>
> Thank you all for your help.
>
> Sincerely,
>
> Liz
>
>
>
> ----
> Elizabeth R. Wright, PhD
> Assistant Professor
> Emory University
> erwrigh at emory.edu <mailto:erwrigh at emory.edu>
> Ph: (404) 727-4665
>
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