[3dem] Ethane - propane mix

[Cindi Schwartz]

Hi all,

Ken had asked about our source of propane. So, we just get it from the local hardware store. It's the 400g bottle. One brand is "Worthington Pro Grade" and the other we have is "Wagon Master Propane Fuel". Then it says on the label: Fits all standard propane heaters, lanterns, stoves and torches. It's really the cheap stuff and we don't get any oil slicks or anything.

Anyway, Mary Morphew says she remembers going to a meeting in Austria some time back where someone was testing propane purity and found that the less pure propane did better freezing--it's what we've used ever since with great success.

As for Ken's final question---it is the propane you use for BBQ or torches, but the small self-contained bottle, not the refillable kinds.

Best,
Cindi


On May 2, 2012, at 11:36 AM, Kenneth Downing wrote:

> Hi Cindi -
>     Since there seems to be such variability with the source of propane, it would be useful to know details of your "high purity" propane from the hardware store - i.e. brand, etc.  Probably something different from the usual barbecue or torch tanks...?
>           Ken
> 
> On 5/1/12 3:43 PM, Cindi Schwartz wrote:
>> 
>> Bill,
>> 
>> We use both routinely. On our manual plunger, it's pure ethane and it seems to work fine (although we routinely freeze the day before we are on the scope--it's very uncommon for us to freeze right before putting the sample in the scope).
>> 
>> We use a ethane/propane mix (60,40) in the vitrobot. In fact, it's high purity ethane and propane we bought at the hardware store that was sitting around in the lab for years. We don't have any contamination issues (mentioned by Bob) and it seems to work fine (meaning consistently vitreous). We also just mix it by eye--usually putting in the propane first and then swirling the ethane in there so it's good and mixed.  
>> 
>> I don't know if that helps, but I guess the reason we don't go direct is b/c with ethane-only freezing, we would crash the vacuum too often so it's become lab protocol to store overnight and then do microscopy.
>> 
>> Hope it helps,
>> Cindi
>> 
>> On May 1, 2012, at 2:02 PM, William Rice wrote:
>> 
>>   
>>> Dear all,
>>> 
>>> Have many of you had experience using a mix of 37% ethane / 63% propane as a cryogen? It has the advantage that it stays liquid at liquid nitrogen temperature. We had thought it would be easier to handle, but we found that it seems to leave a thin layer of liquid cryogen on the surface of the grid. Putting a freshly frozen grid into the microscope seemed to cause problems with the IGP as this liquid seemed to evaporate only in the high vacuum of the microscope. Solid ethane frozen on the grid usually cracks and breaks off or sublimes in the airlock during pumping before insertion. Has anyone else seen this effect?
>>> 
>>> Thanks,
>>> Bill
>>> 
>>> -- 
>>> William J. Rice, Ph.D.
>>> Senior Scientist
>>> New York Structural Biology Center
>>> 89 Convent Avenue, NY, NY 10027
>>> 
>>> 
>>> _______________________________________________
>>> 3dem mailing list
>>> 3dem at ncmir.ucsd.edu
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>>>     
>> 
>> 
>> ****************************
>> Cindi L. Schwartz
>> University of Colorado
>> Dept. MCDB
>> 347 UCB
>> Boulder, CO  80309
>> O: 303-492-7980
>> F: 303-735-0770
>> http://bio3d.colorado.edu
>> ****************************
>> 
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>>   
> 
> -- 
> -------------------------------------------------------------------------------------------
> Kenneth H. Downing
> Life Sciences Division, Lawrence Berkeley National Laboratory
> 112 Donner Lab, Berkeley, CA 94720    tel 510-486-5941; fax 510-486-6488
> 
> UC Berkeley Graduate Group in Comparative Biochemistry
> Senior Associate Editor, Microscopy Research and Technique


****************************
Cindi L. Schwartz
University of Colorado
Dept. MCDB
347 UCB
Boulder, CO  80309
O: 303-492-7980
F: 303-735-0770
http://bio3d.colorado.edu
****************************

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