[3dem] Contamination!

Christian Geiss Geiss at biophysik.org
Thu Mar 7 10:35:31 PST 2013


Hi all,

thanks a lot for this very competent answers. You really help me a lot. Indeed, this too poor glow-discharging
seems to be the problem. It makes totally sense from what I see and what exact parameters I use for plunge-
freezing. I will try that first. 

Thanks a lot,
Chris

----------------ursprüngliche Nachricht----------------- 
Von: "Christian Geiss" geiss at biophysik.org 
An: Frangakis_group at biophysik.org, 3dem at ncmir.ucsd.edu, "Luis González González" luis.gonzalez.g at gmail.com 
Datum: Thu, 07 Mar 2013 15:43:44 +0100 
----------------------------------------------------------

>
>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 geiss at biophysik.org 
>
>__________________________________________________
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>
-- 

Christian Geiss, M.sc.
Universitaet Frankfurt BMLS 


Frangakis Group[ -> http://www.fmls-institute.de/fileadmin/template/images/1px_trans.gif] 


Max-von-Laue-Strasse 15 


D - 60438 Frankfurt am Main 


Phone: +49-(0)69-79842597 


Fax: +49-(0)69-79846467 


geiss at biophysik.org 



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