[Histonet] Decal End Point

Monfils, Paul PMonfils <@t> Lifespan.org
Fri Sep 8 11:44:19 CDT 2006

I'm not sure exactly what you mean.  In the title of your message you
referred to "decal end point", but in the message you said "when a decal
solution is depleted".  The "decal end point" of course would be the point
where all the calcium has been removed from the tissue.  This can be tested
chemically.  However, that isn't the same thing as depletion of the decal
solution.  Decal solutions do not ordinarily become depleted.  In most
cases, the active ingredient in the decal solution is many times the amount
necessary to decalcify the specimens - assuming of course that you use a
sufficiently large volume of decal solution. If you put 5 cc of bone into 10
cc of decal solution, then the solution might become depleted.  An acid
decal solution, if depleted, would theoretically become neutral in pH, but I
have never seen this happen.

I'm assuming that you are actually inquiring about determining the end point
of decalcification.  This can be done by taking 5 cc of the decal solution
from the specimens in a test tube and adding 1 cc of 5% sodium oxalate.  Mix
well and let it stand about a minute.  If it becomes cloudy, the cloudiness
is due to the precipitation of insoluble calcium oxalate. Of course, after
such a test the decal solution must be changed before another test can be
done. When the solution remains clear, no further calcium is coming out of
the tissue, so one can assume that decalcification is complete.  Ammonium
oxalate can also be used in place of sodium oxalate.

> ----------
> From: 	histonet-bounces <@t> lists.utsouthwestern.edu on behalf of
> Traczyk7 <@t> aol.com
> Sent: 	Friday, September 8, 2006 8:36 AM
> To: 	histonet <@t> lists.utsouthwestern.edu
> Subject: 	[Histonet] Decal End Point
> Would someone please supply me with contact information for a company that
> supplies a chemical that will assist in determining when a decal solution
> is 
> depleted? 
> Thanks,
> Dorothy
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