No, there are not any other cations, so I feel very strange. Everything
brought from sigma.
Nothing's strange. EDTA is very poorly soluble at pH 4.2 and would
become even less soluble in the presence of 47% PEG. So it crystallizes.
Dima
On Tue, Feb 22, 2011 at 8:58 PM, William Scott
<<mailto:wgsc...@ucsc.edu>wgsc...@ucsc.edu> wrote:
What other cations are present? Any divalent cations like Mg++ or Ca++?
The Ksp of magnesium phosphate is about 10^-24, so even if you have a very
small amount present, say as a contaminant with citrate or EDTA, it will
crystallize.
On Feb 21, 2011, at 1:22 PM, Yibin Lin wrote:
> Dear all,
>
> I got a lot of salt crystals in reservior solution (well solution),
which contains 0.1 M phosphate/citrate ph 4.2, PEG200 47%, EDTA-2Na
0-22mM. Reservior solution appears crystals from 12mM EDTA. Could someone
help me to explain why?
>
> Thank you very much!
>
> Yibin
>
William G. Scott
Contact info:
<http://chemistry.ucsc.edu/~wgscott/>http://chemistry.ucsc.edu/~wgscott/
