Your 0.1 M Phosphate/citrate can form crystal at high PEG. Deqian
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From: CCP4 bulletin board [[log in to unmask]] On Behalf Of Yibin Lin [[log in to unmask]]
Sent: Tuesday, February 22, 2011 2:24 PM
To: [log in to unmask]
Subject: Re: [ccp4bb] Could someone can help me to explain why EDTA-2Na can formate salt crystals
No, there are not any other cations, so I feel very strange. Everything brought from sigma.
On Tue, Feb 22, 2011 at 8:58 PM, William Scott <[log in to unmask]<mailto:[log in to unmask]>> 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/
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