I went through the peg solid stocks in our cupboard and noticed some of them smelled acrid. I probably won’t use them. Not sure whether they’re chemically decomposing. Maybe fossilising?
Dave David Hargreaves Associate Principal Scientist _____________________________________________________________________ AstraZeneca DECS, CP&SS Mereside, 50F49, Alderley Park, Cheshire, SK10 4TF Tel +44 (0)01625 518521 Fax +44 (0) 1625 232693 David.Hargreaves @astrazeneca.com <mailto:name.surn...@astrazeneca.com> Please consider the environment before printing this e-mail From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Frank von Delft Sent: 24 August 2011 22:21 To: CCP4BB@JISCMAIL.AC.UK Subject: Re: [ccp4bb] Aging PEGs And now, .... does anybody know of systematic data indicating how consistently all this matters? phx On 24/08/2011 21:45, Prince, D Bryan wrote: For those of us truly controlling types :), I used to make the PEG solutions and filter them over a Bio-Rad resin that filtered out all the junk added to stabilize the PEG solution. Then, of course I had to freeze all my PEG solutions in aliquots, or wrap them in foil and store at 4C in the dark. This would take several days, depending on the FW of the PEG. If you are really sensitive about what is in your PEG solutions, try GC-grade PEG's. The FW profile is much more restricted around the reported value (i.e. PEG 3350 molecular biology grade has a broad peak centered on Mr=3350. PEG 3350 GC-grade has a much tighter peak profile.) Back before you could buy Crystal Screen I, II or HT, you had to make the stock solutions, then make the screen. But at least when you did that, you had all the stocks. Now, I just buy pre-made solutions, and keep them in a drawer with a date opened written on the bottle. Isn't progress grand? :) Bryan -------------------------------------------------------------------------- Confidentiality Notice: This message is private and may contain confidential and proprietary information. If you have received this message in error, please notify us and remove it from your system and note that you must not copy, distribute or take any action in reliance on it. Any unauthorized use or disclosure of the contents of this message is not permitted and may be unlawful. -------------------------------------------------------------------------- AstraZeneca UK Limited is a company incorporated in England and Wales with registered number: 03674842 and a registered office at 2 Kingdom Street, London, W2 6BD. Confidentiality Notice: This message is private and may contain confidential, proprietary and legally privileged information. If you have received this message in error, please notify us and remove it from your system and note that you must not copy, distribute or take any action in reliance on it. Any unauthorised use or disclosure of the contents of this message is not permitted and may be unlawful. Disclaimer: Email messages may be subject to delays, interception, non-delivery and unauthorised alterations. Therefore, information expressed in this message is not given or endorsed by AstraZeneca UK Limited unless otherwise notified by an authorised representative independent of this message. No contractual relationship is created by this message by any person unless specifically indicated by agreement in writing other than email. Monitoring: AstraZeneca UK Limited may monitor email traffic data and content for the purposes of the prevention and detection of crime, ensuring the security of our computer systems and checking Compliance with our Code of Conduct and Policies. -----Original Message----- From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Jacob Keller Sent: Wednesday, August 24, 2011 3:18 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Aging PEGs A while ago I measured the pH's of old and new PEGs and found them very different, and internally attributed all "old vs new PEG issues" to pH. Upon reflection, this seems too simplistic. Are there other known mechanisms of crystallization capacities of PEGs of various ages? Jacob Keller ******************************************* Jacob Pearson Keller Northwestern University Medical Scientist Training Program cel: 773.608.9185 email: j-kell...@northwestern.edu *******************************************
