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Wed, 24 May 2006 05:41:51 +0200 |
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Dear Doug,
I tried smectites with laser ablation.
All the samples were dehydrated for 1 day at 200 C in order to clean for absorbtion and interlayer water. I analyzed pure smectite samples (100%), which were not prepared chemicaly before. Also I analyzed separed smectites from soils. Results are the same for different samples: the d18O values are very, very low (??), and there are no reproductible data.
I do not recommed prefluorination with BrF5 because, even the dehydrated smectites will react immediately, so I suspect that oxygen from OH or silicate positions is partly reacting.
A better way: classical silicate line where results are OK after cleaning for one day for interlayer and absorbtion at 200 C and fluorinating for at least 12 hours afterwards.
Ana-Voica Bojar
Dept. of Earth Sciences
Graz University, A-8010
Austria
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