[3DEM] "Gatan" cryopluge

[Lewis, Mike]

A bit more to add to the discussion ...

The Gatan plunger definitely looks like a different setup than the Vitrobot, and I'm sure we'd all like to hear from anyone who has actually used one. We also have a Vitrobot, and our students take one look at the old home made plungers & shudder.

Our experience with the vitrobot has been similar to everyone else's. We settled on a thick soft quantitative (i.e. Ca etc free) paper, Whatman 40, NOT the much harder qualitative S&S paper originally supplied. 90% relative hunidity seems to minimize drying nicely for a wide variety of samples. Finally, we offsets, and they may matter. For a face-on blot, position the grid between the pads near their edge where they make firm contact & compress the rubber backing. Our forceps vary in length from the brass mounting block to the tip from 99mm to 101mm (100 or 101 when new, shorter as repaired). We get a face blot at -2 offset w/101mm forceps (-3 offset w/100mm etc) but just mount a grid do dry runs at different offsets to see where the grid gets positioned. For ours a 0 offset would of course a few mm higher from the edge, where the pads are more separated. That would invite variability with a harder filter paper that doesn't wet & begin wicking immediately. Some of our users are also gripping grids at the side rather that the top (3 o'clock position) in order to have the grids a bit forward of the forceps. On our bot the blot pads meet forward of the forceps rather than immediately below them.  

The advantage/disadvantage of the Gatan probably comes down to pricing vs. taking advantage of the greater experience in this community with the somewhat expensive vitrobots. 

Why not talk Gatan into loaning/demonstration before buying? It might be a nice machine, but I'd want to know that with certainty before buying.

Mike

mike.lewis at vanderbilt.edu
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