[3dem] Contamination!

[Bob Grassucci]

Hi Christian
The blobs you are seeing is from uneven ice as a result of a hydrophobic 
Surface.  Glow discharging should make the surface hydrophilic. Good luck.
Bob
Sent from Bob's IPhone 

On Mar 7, 2013, at 9:43 AM, Christian Geiss <geiss at biophysik.org> wrote:

> Hello,
> 
> I have a persistent problem with grid contamination. In my last preps I can continuously see those contrast-rich big blobbs (0.5 - 1 micrometer; the scale bar in the figure is not right, should be 2 microns instead of 50 nm) in a relatively regular pattern spread all over my grid. I need to say that I am using continuous carbon grids. First I thought it would be oil contamination from the glow discharging or the ethane but my colleagues are using the same chemicals/devices and they don't see it. 
> 
> Another thing then was, that I speculated that it might come from either the 4% formaldeyde (sigma aldrich) or the Triton X-100 that I am using, but can such a chemical form those odd bloobs? More, I also wash my grids with just pH 9 buffered millipore water after I have used each chemical. So I dont really understand when it arises in principal from those chemicals why it lasts on the grid?
> 
> For plunge-freezing I am using a vitrobot mark 4 with 'humidifier during process' set to off. So I am really turning in circles, and I cannot figure out by myself where it might come from? Help is really appreciated.
> 
> Thanks a lot in advance,
> 
> Christian Geiss
> 
> P.S. You can find a picture attached to this mail.
> -- 
> Christian Geiss, M.sc.
> Universitaet Frankfurt BMLS
> Frangakis Group
> Max-von-Laue-Strasse 15
> D - 60438 Frankfurt am Main
> Phone: +49-(0)69-79842597
> Fax: +49-(0)69-79846467
> geiss at biophysik.org
> <030713_overview.jpg>
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