Frances Jurnak published a paper in 1986 on PEG impurities and purification.
As I recall, it turns out that different manufacturers put different
additives in PEGs as preservatives. These are generally anti-oxidants.
PEGs do get oxidized.
I suggest you heat up your new PEG solutions to say 80 deg C and cool them
down, then use them. Let us know what happens.
-----Original Message-----
From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Jun
Yong Ha
Sent: Tuesday, April 12, 2011 6:57 AM
To: [log in to unmask]
Subject: [ccp4bb] Reproducing crystals.
Hi all,
Recently, I produced crystals with MBClass1-64 which contains PEG4000,
HEPES-Na and NaCl. But, I struggled to reproduce crystals. I tried to set up
tray with different batch of solution. I got the crystals only from 2008
solution, but not from fresh ones. I asked technical service of Qiagen, but
they did not have any stock.
pH between fresh and old solution is the same. I could reproduce crystals
with this old solution 100% when setting up.
Do you have any experience like this? Is PEG4000 degraded or oxidized?
Please help me.
Thanks in advance.
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