[3dem] Quality of ethane for freezing

[Bob Grassucci]

Hi All,
Just my 2 cents.  We generally use research grade which I believe is 
99.95% to avoid the contaminants from the bottom.  This grade takes 
longer to get and is more expensive.  You start seeing these 
contaminants with lower grades if your tank is close to empty or if you 
have moved the tank very recently (1-2 hours?).  Moving the tank stirs 
up what is on the bottom.  In order to avoid contamination we order the 
higher grade so we can get the full use of the tank and move it around 
at will. Just personal preference. My guess as to the difference in 
grades is only if they clean out the old tank before filling back up for 
the higher grade;)  You could get lucky with a lower grade?
Bob

On 2/1/2013 11:55 AM, Ariane Briegel wrote:
> Dear Esther,
> we had similar issues a few years back. If I remember correctly,the 
> "pure CP Ethane" label of the ethane changed to  99%  purity, whereas 
> older "pure CP Ethane" was specified  99.5%.
> After we ordered a higher grade ethane, there contamination issues 
> disappeared.
>
> We also use an ethane/propane mix in the lab- this mixture doesn't 
> freeze at all and we have great success using it:
> An improved cryogen for plunge freezing. Microscopy and Microanalysis 
> : the Official Journal of Microscopy Society of America, Microbeam 
> Analysis Society, Microscopical Society of Canada, 14(5), 375--379.
> Good luck!
>
>
> --------------------------------------------------------
> Ariane Briegel, Ph.D.
> California Institute of Technology
> Broad Center, MC 114-96
> 1200 E. California Blvd.
> Pasadena, CA 91125
>
> Tel: 626-395-8848
> Fax: 626-395-5730
> --------------------------------------------------------
>
>
>
> On Feb 1, 2013, at 8:22 AM, Bullitt Esther wrote:
>
>> Hi,
>>
>> We have always bought technical grade ethane rather than the high 
>> purity.  By the bottom of the tank, the grids have contamination, and 
>> so we switch it out.
>>
>> This last time, the tank cost half the price, and has been showing 
>> contamination pretty soon after we started using it.  Perhaps it is 
>> now a lower grade.
>>
>> Do people recommend buying the high purity ethane?  My understanding 
>> is that it then freezes very rapidly, so one must contend with 
>> thawing it often.
>>
>> thanks,
>> Esther
>>
>> ---
>> Esther Bullitt, Ph.D.
>> Dept. of Physiology & Biophysics
>> Boston University School of Medicine
>> 700 Albany Street, Room W302
>> Boston, MA  02118-2526
>>
>> Email: bullitt at bu.edu <mailto:bullitt at bu.edu>
>> Telephone:  617-638-5037
>> Facsimile:  617-638-4041
>> http://www.bumc.bu.edu/phys-biophys/faculty/bullitt
>>
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>
>
>
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