[3dem] Insertion of Holder 626

[Savva, Christos (Dr.)]

Hi Ariel

To add to Krishna’s comments the airlock my also need a clean. I recently had frequent vacuum crashes on our CM200 and a careful clean of the airlock tube removed a lot of particulates that were the cause of the problem.

I would recommend you ask you field service engineer to clean it as there are some sensitive components that you don't want to damage.

Best wishes

Christos

Dr. Christos Savva
Facility Manager
Midlands Regional Cryo-EM Facility
University of Leicester
Henry Wellcome Building
Lancaster Road
Leicester, LE1 7HB

t: +44 116 229 7109
e: gwcs1 at le.ac.uk<mailto:gwcs1 at le.ac.uk>
w:www.le.ac.uk/cryoem<http://www.le.ac.uk/cryoem>

On 24 Feb 2020, at 13:13, TALAVERA PEREZ Ariel <Ariel.Talavera at ulb.be<mailto:Ariel.Talavera at ulb.be>> wrote:

Dear all,

I am using a Gatan 626 holder on a side entry TALOS microscope. I am
getting problems with very frequent crystalline ice formation on the
grids. Some times I get a mix of vitreous and crystalline water, but
must of the time I only get crystalline water. I have been extra careful
during sample preparation, and transferring the grind on to the holder,
and I have done 48 hours holder bake out before insertion, but I still
get ice on the grid.

I monitored the temperature of the holder during the insertion process,
including 3 minutes for the Airlock pump. During those 3 minutes the
temperature rises up to -152.2. Can this be the reason of the unwanted
ice formation? How high can be the temperature of the holder to ensure a
nice vitreous water?

I am also getting vacuum problems while inserting the holder. This
process has resulted to be extremely, extremely sensitive. After the 3
minutes Airlock pumping (I cannot give longer time because of the
aforementioned temperature issue) as soon as I open the column port the
vacuum either rises to 99 Log or completely crashes the column vacuum.
This has happened with two different holders either cooled with liquid
nitrogen or at room temperature. So, my question: Is this insertion
process always that  picky or it can be that there is something wrong
with the holders/Airlock pump?

Thanks a lot in advanced.

Best regards.

Ariel

--
Ariel TALAVERA PEREZ, PhD
Center for Microscopy and Molecular Imaging (CMMI)
Laboratory of Microscopy
Université Libre de Bruxelles
Rue Adrienne Bolland, 8
B-6041 Gosselies, Belgium
Phone +32 (0)26509866

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