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|Author||Topic:Isotopic Fractionation||1052 Views|
30 June 2011 at 12:46pm
On the isotope analysis issue, do the porous cups cause isotopic fractionation?
1 July 2011 at 9:55am
The short answer is a qualified no. Pore water is taken by the samplers via mass flow (water tension), and conventional wisdom is that isotope fraction is negligible by mass flow IF there is no interaction between the cup and the substrate. If you have small organic molecules interacting with a ceramic cup then you may very will get isotopic fractionation. Cup selection is critical here. Larger molecules (polymers or multi-unit organics) will be less susceptible to isotopic fractionation.
6 July 2011 at 11:11am
I thought about this some more over the weekend and I am not so sure that you wouldn't see a fractionation if you are looking at D or 180 at natural abundances. I can imagine the cup matrix and tension acting very much like a mini (make that micro) chromatography column. I think a test of the effect would definitely be in order. It shouldn't be too hard. A sealed container with known delta-D and 18O would give you a good idea of any effects and their magnitude. I would love to hear how this turned out. The solutes I don't think would be affected as long as they don't interact with the column.
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