Re: End Point Determination when EDTA decalcified

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From:Lesley Weston <lesley@interchange.ubc.ca>
To:Mary Stevens <mstevens@genetics.com>
Reply-To:
Date:Tue, 28 Sep 1999 16:53:19 -0700 (PDT)
Content-Type:TEXT/PLAIN; charset=US-ASCII

I think the purpose of the citrate phosphate buffer is to lower the pH so that
the EDTA will release the Ca ions, allowing them to react with the oxalate ions
and precipitate. So you just need any buffer at a really low pH, such as the
ones in Culling. Hope this helps.

Lesley Weston.


On Tue, 28 Sep 1999, Mary Stevens wrote:

> If you have xray equipment available (a Faxitron works great) try that, after a couple uses, it'll take much less time than the end point testing, is more reliable, and is a nice way to document the decal progress.
> 
> Mary
> 
> >>> <Rose_Bellantoni@integra-ls.com> - 9/27/1999 6:20 PM >>>
> Dear Histonetters,
> 
> I am in need of a recipe for a citrate-phosphate buffer solution that is
> used with a saturated aqueous ammonium oxalate solution for end point
> determination of EDTA decalcified specimens.  I have a article that
> describes this method but it neglects to give the amounts needed to make up
> the buffer.
> 
> This procedure calls for 0.5 ml of spent EDTA solution to be mixed with 1.0
> ml of citrate-phosphate buffer and 2.5 ml of saturated aqueous amonium
> oxalate.  If calcium is present in the test tube, a cloudy white precipate
> will form.  A clear solution after 20 minutes indicates the absence of
> detectable calcium in the decalcifying solution.
> 
> Or, does any one have another tried and true procedure for EDTA end point
> testing?
> 
> Thanks so much, again.
> 
> Rose Bellantoni
> 
> 
> 
> 
> 
> 
> 
> 
> 




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