[3dem] Thoughts on Gatan Cryoholders (CT3500 and 626)

[Matthias Wolf]

Hi Heather,

I second Yifan's opinion. I have also used both holders and the 3500 needs more careful handling. I know of many service calls. Little saphire bearings can come loose, the dewar lid can pop when heated too fast, hair-thin wires inside can break or melt. But otherwise it is a great holder when used with care.

The 626 appears to have a more robust design and it is significantly easier to load grids. While the 3500 seems to have a better designed (better insulating) dewar and might therefore be more stable in resolution tests, the 626 comes close (I got a 3.5A virus reconstruction out of it and this was a "2nd grade" holder). In particular the newer generation has, in my opinion, equal stability and lasts easily 90 min between refills. Gatan has apparently changed the desiccant to an activated carbon based substance in the newer ones, which increases baking intervals and improves dewar vacuum and holder stability. Subjectively I like the holder with the new desiccant better (I have used 626 with both fillings). I think Gatan can exchange the desiccant in older holders. Combined with its higher tilt capability, I'd choose the 626.

Cheers,
   Matthias

-- 
_________________________________________________
Matthias Wolf, PhD - Postdoctoral Research Fellow
Harrison Laboratory
BCMP, Harvard Medical School
Seeley G. Mudd 130
250 Longwood Ave. Boston, MA 02115

On Sep 17, 2010, at 2:53 PM, Cheng, Yifan wrote:

> We have both CT3500 and 626. CT3500 is more suitable for high resolution work, while 626 can tilt to higher angle. I noticed that the new CT3500 can also be tilted to 50 or even 60 degree, and 626 has a better design in the dewar and is more stable than older version. So, I would say that both CT3500 and 626 are improved compared with their earlier generation. Gatan’s specification of both holders are the same, 3.4A at LN temperature. But we got 2.3 from our CT3500, just like the original CT3500 from Oxford. Surprisingly, 626 gives also good resolution, better than 3.4A.
> 
> In general, CT3500 is more stable, but harder to handle. 626 is easier to deal with but less stable. Nevertheless, performance is still dependent on individual holders, or as always, depends on how lucky are you.
> 
> The problem for CT3500 is that it is very fragile. If you have a large user group, it is very likely that your CT3500 would be traveling a lot between your lab and Gatan. If you would like to have CT3500, it is better to have two. Although sounds ridiculous, but you will find this is actually necessary. Because, most likely, one of the two will be on the trip at any given time.
> 
> Good luck,
> 
> Yifan
> 
> 
> On 9/17/10 9:55 AM, "Heather Holdaway" <hah46 at case.edu> wrote:
> 
> I am looking for insight on comparing two of Gatan's cryoholders: the CT3500 and the 626.  Is anyone willing to share the pros and cons of the two holder with me?  Or if you were going to be purchasing a holder, which would you choose?
> 
> Thanks for the input!
> Heather
> 
> 
> 
> ************************************************************
> Yifan Cheng, Ph.D.
> University of California San Francisco
> Department of Biochemistry and Biophysics
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> 
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