It's a little complicated. It's true that oxygen is more soluble in most oils than in water - but in a high viscosity mineral oil the diffusion rate is orders of magnitude lower. So the combination of an oil overlay and a reducing agent in your buffer should protect your sample much longer than the reducing agent alone - as long as your oil was degassed to start with. Note that silicon oils are a bad choice for this - silicones have an enormous affinity for oxygen (so much so that they've been explored as artificial blood substitutes), and it diffuses through them very readily.
Tristan Croll Lecturer Faculty of Health School of Biomedical Sciences Institute of Health and Biomedical Engineering Queensland University of Technology 60 Musk Ave Kelvin Grove QLD 4059 Australia +61 7 3138 6443 This email and its attachments (if any) contain confidential information intended for use by the addressee and may be privileged. We do not waive any confidentiality, privilege or copyright associated with the email or the attachments. If you are not the intended addressee, you must not use, transmit, disclose or copy the email or any attachments. If you receive this email by mistake, please notify the sender immediately and delete the original email. > On 18 Mar 2015, at 11:49 pm, Edward A. Berry <ber...@upstate.edu> wrote: > > Do you have evidence that the oil blocks diffusion of O2? O2 is a nonpolar > molecule, generally much more soluble in oils than in water. I'm not sure > about silicone oils, but I would think they also dissolve O2 readily. > eab > >> On 03/18/2015 08:02 AM, Patrick Shaw Stewart wrote: >> >> Hi Steve >> >> I have one more comment for this thread. >> >> The microbatch-under-oil method is very handy for anaerobic work: >> >> 1. You can keep the microbatch stock solutions in normal microtitre >> plates (polypropylene is best to reduce evaporation) for months, which >> hugely reduces the amount of degassing that you need to do. You will only >> use say 0.5 ul of stock per drop. >> >> 2. The oil offers a surprising amount of protection from oxidation, >> which may be helpful eg in harvesting. >> >> 3. Microbatch can be automated - in parallel to vapor diffusion if >> desired >> >> >> It's amazing how often (aerobic) microbatch produces far superior crystals >> to V.D. for no obvious reason - it's well worth trying for both screening >> and optimization. >> >> Best wishes >> >> Patrick >> >> >> >> On 11 March 2015 at 10:17, <Stephen Carr> <stephen.c...@rc-harwell.ac.uk >> <mailto:stephen.c...@rc-harwell.ac.uk>> wrote: >> >> Dear CCP4BBer's >> >> Apologies for the off-topic post, but the CCP4BB seems to be the best >> place to ask about crystallisation. >> >> I am looking to set up crystallisation in an anaerobic glove box and >> wondered how other people did this, specifically the crystallisation stage. >> My initial thoughts were to place a small crystallisation incubator inside >> the box, however the smallest I have come across so far (~27L) is still >> rather large. Has anyone come across smaller incubators? Alternatively are >> incubators even neccessary if the glove box is placed in a room with good >> air conditioning and stable temperature control? >> >> Any recommendations would be very helpful. >> >> Thanks in advance, >> >> Steve Carr >> >> Dr Stephen Carr >> Research Complex at Harwell (RCaH) >> Rutherford Appleton Laboratory >> Harwell Oxford >> Didcot >> Oxon OX11 0FA >> United Kingdom >> Email stephen.c...@rc-harwell.ac.uk <mailto:stephen.c...@rc-harwell.ac.uk> >> tel 01235 567717 <tel:01235%20567717> >> >> This email and any attachments may contain confidential, copyright and or >> privileged material, and are for the use of the intended addressee only. If >> you are not the intended addressee or an authorized recipient of the >> addressee, please notify us of receipt by returning the e-mail and do not >> use, copy, retain, distribute or disclose the information in or attached to >> this email. >> >> Any views or opinions presented are solely those of the author and do not >> necessarily represent those of the Research Complex at Harwell. >> >> There is no guarantee that this email or any attachments are free from >> viruses and we cannot accept liability for any damage which you may sustain >> as a result of software viruses which may be transmitted in or with the >> message. >> >> We use an electronic filing system. Please send electronic versions of >> documents, unless paper is specifically requested. >> >> This email may have a protective marking, for an explanation, please see: >> >> http://www.mrc.ac.uk/About/informationandstandards/documentmarking/index.htm. >> >> >> >> >> -- >> patr...@douglas.co.uk <mailto:patr...@douglas.co.uk> Douglas Instruments >> Ltd. >> Douglas House, East Garston, Hungerford, Berkshire, RG17 7HD, UK >> Directors: Peter Baldock, Patrick Shaw Stewart >> >> http://www.douglas.co.uk >> Tel: 44 (0) 148-864-9090 US toll-free 1-877-225-2034 >> Regd. England 2177994, VAT Reg. GB 480 7371 36
