[Histonet] Decal End Point

[McCormick, James]

All, I think they are talking about the point at which there are no more
calcium ions liberated into the  electrolyte  solution (acid+H2O). If
there was a meter on the bath, as in a plating tank, there would be a
distinct end point signaled by a Change in the electrolytic process.
This is ,in fact,  the end point of a titration of the bone fixed
calcium that has been converted into a soluble calcium salt.  At some
point in the past years I have seen an electrolytic "fast" bone
decalcifyer that worked this way.
Many things have gone over the work bench of the years, only to be
discovered or reinvented !
J.B.McCormick M.D.

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Monfils,
Paul
Sent: Friday, September 08, 2006 10:44 AM
To: 'histonet <@t> lists.utsouthwestern.edu'
Subject: RE: [Histonet] Decal End Point

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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> Histonet <@t> lists.utsouthwestern.edu
> http://lists.utsouthwestern.edu/mailman/listinfo/histonet
> 
> 

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