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Last updated 10/29/2020
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Gatan CT-3500 (Oxford) holder manual
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This holder takes ~30 min to cool down and should be done while plugged into the temperature
controller to monitor cooling.
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It is nearly impossible to recover grids from the CT-3500 holder. Thus, if the grid is good you
should plan to collect rather than save the grid.
1. Remove holder from dry pumping station.
a. At the beginning of the day, the temperature control readout should be at 50°C (bake out
from the night before). Turn the controller off and then back on so as to stop the heating.
Once turned back on you should see the temperature drop from 50°C. Wait until temp drops
to at least 30°C before cooling down the holder.
b. Close V4, V3 and then V1 of the dry pumping station. V2 should already be closed, but if
not, then close V2.
c. Unhook tygon tubing from holder and re-connect to silver stopping plug (near V1 & V2)
d.
Turn the pumping station off and wait for the green “MDP ready” light to turn off
e. Using one hand to stabilize V1/V2 vacuum area, gently apply force to pull out cryo-holder.
Open the holder entry valve on the workstation and insert the holder
f. Immediately upon removing cryo holder, store in cryo transfer station
g. Place blanking plug (black) into opening where cryo holder was
h. Disconnect the silver/black/red vacuum adapter off of the holder. See image.
2. Cool down holder to at least -160°C.
a. Cool down the holder with it connected to the temperature controller module to adequately
measure temperature. Cool down the dewar/jacket of the holder using a funnel. SLOWLY,
cool down the tip of the holder using the cylindrical filling cup until the temperature reads
at least -160°
C (takes ~ 30 min). Make sure that while the tip is cooling down, that there
is a steady droplet of liquid nitrogen pouring onto the tip of the holder. See image →