Dear Andrew, To help you with your question one would need to know a few more specifics such as chemical nature of the organic solid and d2H values of the 2 waters A and B used for the exchange experiment for starters. You are welcome to contact me off-line if you feel you cannot share the specifics of your experiment with the list. Best, Wolfram ****************************************************** Prof. Dr W Meier-Augenstein, CChem, FRSC Stable Isotope Forensics & Analytical Sciences Robert Gordon University School of Pharmacy and Life Sciences The Ian Wood Building Garthdee Road Aberdeen AB10 7GJ E-mail: [log in to unmask] ________________________________________ From: Stable Isotope Geochemistry <[log in to unmask]> on behalf of A.J. Tanentzap <[log in to unmask]> Sent: 19 December 2018 19:35:02 To: [log in to unmask] Subject: [ISOGEOCHEM] help interpreting 2H exchange exp't Dear all I've run an exchange experiment on a solid organic as described in Meier-Augenstein et al. 2011. Rapid Commun Mass Spectrom. I estimated the non-exchangeable 2H ratio to be -178. The estimated fraction of exchangeable H in the sample was 0.0005. When I re-run the sample in a bulk analysis, the total (i.e. exchangeable + non-exchangeable) ratio was -190. Would someone be so kind as to explain how this is possible with a near-zero fraction of exchangeable H? Many thanks! Andrew ---------- This email has been scanned for spam and viruses by Proofpoint Essentials. Visit the following link to report this email as spam: https://eu1.proofpointessentials.com/index01.php?mod_id=11&mod_option=logitem&mail_id=1545248132-5yKLNHey8OjX&r_address=w.meier-augenstein%40rgu.ac.uk&report=1 ________________________________ Robert Gordon University has been awarded a TEF Gold award for the quality of its undergraduate teaching and learning, placing it in the top 20% of Universities in the UK Robert Gordon University, a Scottish charity registered under charity number SC 013781. This e-mail and any attachment is for authorised use by the intended recipient(s) only. It may contain proprietary material, confidential information and/or be subject to legal privilege. It should not be copied, disclosed to, retained or used by, any other party. If you are not an intended recipient then please promptly delete this e-mail and any attachment and all copies and inform the sender. Please note that any views or opinions presented in this email are solely those of the author and do not necessarily represent those of Robert Gordon University. Thank you.