lyophilizing leaf tissue

Dr Engelbert Buxbaum via methods%40net.bio.net (by engelbert_buxbaum from hotmail.com)
Thu Nov 26 11:34:24 EST 2009


Am 24.11.2009, 09:46 Uhr, schrieb Jeremy Coate <coatej from gmail.com>:

> Hi savy methodologists,
>
> I need to lyophilize leaf tissue prior to shipping overseas. The tissue  
> will
> be used for analysis of lipids, which are vulnerable to endogenous  
> lipases,
> so I am planning to collect the tissue into liquid N2, freeze dry and  
> ship
> on dry ice to try to ensure that these lipases don't have a chance to do
> their thing. I have never used a lyophilizer and have concerns that I'm
> using it incorrectly, and that the samples are thawing.
>
> I'm using a Labconco FreeZone 18 freeze dryer with a bulk dryer unit on  
> top

You should have somebody show you how to use the instrument correctly.  
That only takes 2 min, rocket science it ain't. Lyophilizers consist of a  
vacuum pump and a cold trap. You connect your deep frozen sample to it,  
and the solvent (water in your case) sublimates. The vapor is condensed in  
the cold trap, which has to be cleaned from time to time. All the heat  
coming into your sample from the environment is used to increase the  
sublimation rate, the heat of evaporation ensures that the sample stays  
frozen until all solvent has been removed.

In your case however, it perhaps would be more appropriate to extract the  
lipids and ship those. See
@article{Rad-81,
         AUTHOR= {M.S. Radin},
         TITLE= {Extraction of tissue lipids with a solvent of low  
toxicity},
         YEAR= {1981},
         JOURNAL= {Meth. Enymol.},
         PAGES= {5-7},
         VOLUME= {72},
         LANGUAGE= {engl}
}
which uses cyclohexane rather than chloroform as in
@article{Bli-59,
         AUTHOR= {E.G. Bligh and W.J. Dyer},
         TITLE= {A rapid method for total lipid extraction and  
purification},
         YEAR= {1959},
         JOURNAL= {Canadian J. Biochem. Physiol.},
         PAGES= {911-917},
         VOLUME= {37},
         NUMBER= {8},
         LANGUAGE= {engl}
}
The trick with all these procedure is to work under nitrogen, to prevent  
lipid peroxidation.


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