I agree with most comments so far but would add that we typically use
sucrose as our oxygen isotope standards in most runs of organic
material. This seems to have a reasonable accuracy and precision if
well cared for, and is appears to be less hygroscopic than cellulose.
This probably results from having a much lower surface area as it is
crystalline and not based on micro-fibres. As cellulose is a glucose
polymer, I think it reasonable to assume that decomposition of sucrose
(fructose/glucose dimer) and cellulose is reasonably similar under
It is pretty clear that you cannot produce, much less store, a
water-free cellulose. The relationship between water and the cellulose
structure is much too intimate.
Please feel free to disagree: Willi, Tyler and I have discussed the use
of sucrose as an 18O standard at some length and it was NOT included in
the IUPAC study that Willi mentioned because of its limitations.
Like Paul, we try to keep our standard dry and emphasise repeatability
We have a working value of 36.4 permil VSMOW for the ANU Sucrose
standard, which I believe is similar to IAEA-CH-6?
Hilary Stuart-Williams PhD
Research Officer - Stable Isotopes
Environmental Biology Group
Research School of Biological Sciences
The Australian National University
Australia ACT 2601
Office 61 02 6125 2099
Fax 61 02 6125 4919
Mobile 0421 905 478