[3dem] Quality of ethane for freezing
David Belnap
dbelnap at cores.utah.edu
Fri Feb 1 10:23:08 PST 2013
Small oil droplets from vacuum pumps can also be a problem. When a similar issue came up a few years ago, someone commented that they moved the vacuum pump for the glow discharger into a hood. My lab had the vacuum pump within two meters of our Vitrobot. We moved the pump and glow discharger into a hood and saw a reduction in grid contamination on our cryo grids.
David
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David M. Belnap
Electron Microscopy Core Facility
Department of Biochemistry
Department of Biology
5C124 School of Medicine
University of Utah
Salt Lake City, Utah 84132 USA
Phone 801.585.1242
FAX 801.585.6364
David.Belnap at utah.edu<mailto:David.Belnap at utah.edu>
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On Feb 1, 2013, at 11:11 AM, Ruben Diaz-Avalos wrote:
I have seen some very clean grids that were frozen with propane from the Waltham Supermarket (i.e. a very generic one), as well as some rather dirty grids frozen with ethane of the highest purity grade. My feeling is that it might not even be the ethane that is at fault in many cases (perhaps the fault lies on the grids, which can also vary within the same batch?). However, I am convinced that it is better to purchase the ethane with the highest purity, if only to avoid the nagging feeling that the experiments might have been ruined by frugality.
Ruben.
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Ruben Diaz-Avalos, Ph.D.
Department of Molecular and Cellular Biology,
Briggs Hall,
University of California, Davis,
1 Shields Avenue,
Davis, CA 95616
Phone: (530)752-8282
Cell: (917)515-6353
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On Feb 1, 2013, at 9:28 AM, Cindi Schwartz wrote:
To Ariane's point, we also use the ethane/propane mix with great success, but I confess we just use the propane you can buy at the hardware store. I'm feeling like our grids look fine. We use the highest purity ethane we can find, though.
Cindi
On Feb 1, 2013, at 9:55 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!
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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
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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
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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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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<http://bio3d.colorado.edu/>
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