X-Message-Number: 8515
From: "Gerald Olschewski" <>
Date: Mon, 1 Sep 1997 12:36:28 +0200
Subject: Re: CryoNet #8511

In message 8511 Yvan Bozzonetti wrote:

> Yes LN2 is corrosive on a long time basis. Cells have been preserved at LN2
> temperature, not in direct contact with LN2. Cell samples are most often
> put in glass tubes for that purpose.

Dear Yvan,

I think you are mistaken here... LN2 isn't toxic at all, neither in 
the short nor in the long run. Also, LN2 doesn't show any corrosive 
properties, at least not at normal or moderately elevated pressure.
The reason, why samples are put in glass tubes is the following:
First, it protects the samples mechanically and prevents them from
getting mixed up. If you notice that samples deteriorate in direct 
contact with LN2 over longer periods of time, then the reason for 
this is, that most containers aren't pressure-sealed for the sake of
simplicity. Thus oxygen out of the surrounding air with it's higher
condensation point, diffuses into the LN2. This oxygen that is 
resolved in the nitrogen is the actual reason why this "mixture" 
may show corrosive properties. This effect could be completely 
avoided by consequently working under oxygen-free conditions.

Greetings,

       Gerald Olschewski

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Gerald Olschewski, M.Sc.
Department of Anorganic Chemistry
University of Regensburg/Germany

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