[Histonet] Urea and nitric acid

Gayle Callis gcallis <@t> montana.edu
Mon Aug 6 10:52:21 CDT 2007

Hi Cheryl,

I have never used urea in nitric acid, but simply 5% nitric acid, any 
higher concentration is a bit too concentrated.   However, if the stock 
nitric acid has a yellow color to start with, DON'T use it.  The yellow 
color means the acid is old and you should use new stock instead.  Plus you 
may never get rid of the yellow discoloration.

There is a nitric acid decalcifier caller Perenyi's (1882!) that gave us 
wonderful results years ago in a study, and is a bit gentler than 5% nitric 

Nitric acid, 10%      40 ml
Absolute ethanol      30 ml
0.5% chromic acid    30 ml

We did decalcification endpoint determinations with this decalcifier, and 
had brilliant staining results.

  At 09:21 AM 8/6/2007, you wrote:
>Hi - For those of you who decalcify a lot.   I have a graduate student who
>want to decalcify temporal bone from a dog using a protocol that uses 5%
>nitric acid and urea.   The urea is supposed to clear the nitric acid color.
>  Our question is - is there a specific urea what should be used.   Having
>never used it myself, I have no idea what to buy.

Gayle Callis
Research Histopathology Supervisor
Veterinary Molecular Biology
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610

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