Re: pH of EDTA

From:Barry Rittman <brittman@admin4.hsc.uth.tmc.edu>

Hey Ronnie be nice, this looks like a person asking for help.

Eileen,
EDTA is a white powder that  is only slightly soluble in distilled
water. If the pH is raised such as with sodium hydroxide the pH will
change and some of the EDTA will have groups replaced with sodium and
some of the powder wll have dissolved in the process. There are four
potential groups to be replaced with sodium. Replace one group and you
have mono sodium , two disodium, three tri sodium and four tetra sodium
EDTA.   You can adjust the pH anywhere from pH 2.65 through pH 10.7. If
you are asking re EDTA in  decalcification, then pH 7.2 to 7.4 is
commonly used and contains a mixture of di and tri sodium EDTA. Most
individuals do not start with EDTA but with disodium EDTA and adjust the
pH with sodium hydroxide.
Barry

Ronnie Houston wrote:

> How long is a piece of string???????
>
> Ronnie Houston
> Cytochemistry & Molecular Pathology
> Texas Scottish Rite Hospital for Children
> 2222 Welborn Street
> Dallas, TX 75219
> (214) 559 7744
> (214) 559 7768 - fax
> ronnie.houston@tsrh.org
>
> >>> <Eileen_Dusek@cdh.org> 08/15/01 08:38AM >>>
> HI Everyone,
>  A quick question,
> Does anyone know the pH of EDTA?
>
> Thanks
>
> Eileen Dusek
> CDH





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