[3dem] ethane-propane mix -summary
rice at nysbc.org
Wed May 2 16:25:57 PDT 2012
Thanks to everyone for your replies! This seems to be a more interesting
topic than I expected.
To summarize, it seems several groups do use a mixture of ethane /
propane without problem. Several blot away excess liquid from the grid
by touching to a small piece of filter paper under liquid nitrogen
directly after blotting. Another solution is to not be impatient and
wait overnight before putting the sample in the microscope. A dull pair
of forceps may help since they may not wick up as much liquid.
A good idea from Cindi and others is to use pure or store-bought
propane and manually mix it with ethane after liquifying. This seems
better and cheaper than having a specific tank mix. She specifically
bought "Worthington Pro Grade" and "Wagon Master Propane Fuel", but
apparently there was no special need for high purity.
Other brought up the problems of contaminants in the gases causing oil
slicks and blobs on the frozen grids. Also to keep the cryogen cup clean
of oil contaminants by cleaning or plasma cleaning if available.
William J. Rice, Ph.D.
New York Structural Biology Center
89 Convent Avenue, NY, NY 10027
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