[3dem] Ethane - propane mix

[William Rice]

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