[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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