Though I haven’t heard from you, I thought my suggestion might still prove helpful; if not for you then for colleagues facing similar problems.
Unless one wishes to go for maximum bang for one’s effort (exchange correction and scale normalization in one go), the situation you are facing can be solved without a keratin standard with a true, non-ex d2H value of about +60 ‰.
The keratin standards you are using are perfectly adequate to deal with correction for exchangeable hydrogen based on the comparative equilibration method using 100 % matrix matched standards. Scale normalization of measured d2H values can be achieved in a separate step by including reference waters in silver tubes such as USGS48 and USGS49 as part of the batch run; these reference waters are available from the Reston lab.
Our lab has been measuring hydrogen isotopes on bird claws recently that fall well outside the range of our current reference materials. We currently use two keratin reference materials (CBS, δD = -197 and KHS, δD = -54.1‰) when running feathers and claws. Some of the claws we’ve analyzed have had δD values as high as + 50 to 60‰. Is anyone aware of any keratin reference materials that have δD around + 50 to +70‰?
Robin B. Trayler
Stable Isotope Laboratory
Department of Geosciences
Boise State University, Boise, ID
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