Your 0.1 M Phosphate/citrate can form crystal at high PEG. Deqian ________________________________________ From: CCP4 bulletin board [CCP4BB@JISCMAIL.AC.UK] On Behalf Of Yibin Lin [yyb...@gmail.com] Sent: Tuesday, February 22, 2011 2:24 PM To: CCP4BB@JISCMAIL.AC.UK 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 <wgsc...@ucsc.edu<mailto: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/