[3DEM] A question about the samples for STEM studies

[Bill Tivol]

On Nov 22, 2005, at 7:41 AM, Hu, Guobin wrote:

> I guess some of us are also STEM experts, I’d like to learn something 
> about STEM from you.  
> I have a question regarding STEM studies, specifically for 
> mass-per-length (MPL) analysis by STEM. What are the effects of salt 
> and sucrose in sample buffer? For example, if the sample buffer 
> contains 500 mM NaCl and 500 mM sucrose, how the salt and sucrose 
> could affect the MPL analysis by STEM?
> Thanks for your attention. Any response will be greatly appreciated!
>
Dear Guobin Hu,
	I am not a STEM expert, but to determine the effects of the salt and 
sucrose to a reasonable approximation, you can just use the density of 
the solution, and multiply by the thickness to get a mass-per-length 
number.  The easiest way to get the density is to weigh the amount 
delivered by a pipette, say 100 uL, and divide that by the weight of 
the same amount of water.  This will require that no buffer sticks to 
the pipette tip.
Yours,
Bill Tivol, PhD
EM Scientist and Manager
Cryo-Electron Microscopy Facility
Broad Center, Mail Code 114-96
California Institute of Technology
Pasadena CA 91125
(626) 395-8833
tivol at caltech.edu
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