During a prior period of great concern about variable peroxidation levels of commercial PEGs (and of polyoxyethylene detergents), we measured/monitored peroxide levels of solutions. The Pierce kit is now available from Fisher https://www.fishersci.com/shop/products/pierce-quantitative-peroxide-assay-kit-aqueous/PI23280#?keyword=Peroxide%20Assay%20Kit or you could DIY if you like. This was, of course, in addition to making small amounts of stock solutions + using brown glass (not plastic) for storage.
Good luck with your bedeviling issue. Regards, -MW ------ Michael C. Wiener, Ph.D. Professor of Molecular Physiology and Biological Physics University of Virginia PO Box 800886 Charlottesville, VA 22908-0886 434-243-2731 (office) 434-243-2730 (lab) From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> on behalf of David Briggs <david.bri...@crick.ac.uk> Reply-To: David Briggs <david.bri...@crick.ac.uk> Date: Tuesday, March 23, 2021 at 4:20 AM To: "CCP4BB@JISCMAIL.AC.UK" <CCP4BB@JISCMAIL.AC.UK> Subject: Re: [ccp4bb] Fluka-branded PEG 3000 Hi Galen, Is it possibly the age of the original material, rather than the batch or brand? PEG does oxidise over time. Best, Dave -- Dr David C. Briggs Senior Laboratory Research Scientist Signalling and Structural Biology Lab The Francis Crick Institute London, UK == about.me/david_briggs ________________________________ From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> on behalf of Correy, Galen <galen.cor...@ucsf.edu> Sent: Monday, March 22, 2021, 17:10 To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Fluka-branded PEG 3000 External Sender: Use caution. Dear all, I'm wondering if anyone could spare 50-100 g of Fluka branded PEG 3000 (see attached image)? We have some crystals that diffract better when grown using Fluka PEG compared to other brands. Unfortunately, we've exhausted our supply of the Fluka PEG, and it's no longer commercially available (the same product code is available from Sigma - we've tested it, along with several other brands - but they don't seem to have the same magic as the Fluka PEG). We'll happily purchase a new bottle of Sigma-branded PEG 3000 to replace any sent our way. Many thanks, Galen ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1<https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.jiscmail.ac.uk%2Fcgi-bin%2FWA-JISC.exe%3FSUBED1%3DCCP4BB%26A%3D1&data=04%7C01%7C%7Cf38952d06e4a4be94b7b08d8ed557387%7C4eed7807ebad415aa7a99170947f4eae%7C0%7C1%7C637520298573799761%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=jGHZ8nmg8E9gts4X1KjhQPbDBH8axxuHz9GDoaeopk4%3D&reserved=0> The Francis Crick Institute Limited is a registered charity in England and Wales no. 1140062 and a company registered in England and Wales no. 06885462, with its registered office at 1 Midland Road London NW1 1AT ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
