Caution on the use of Viton® or FETFE® O-rings in carbon dioxide sample containers for δ 18 0 analysis

Kinga M. Revesz; Tyler B. Coplen

doi:10.1016/0168-9622(91)90054-z

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Caution on the use of Viton® or FETFE® O-rings in carbon dioxide sample containers for δ 18 0 analysis

Kinga M. Revesz·Tyler B. Coplen

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Abstract

After 10 days, 3-μmol CO 2 samples in containers having glass stopcocks with Viton ® or FETFE O-rings were enriched in 18 O by 1.5% as a result of absorption by the elastomer; this amount of enrichment is &sim;20 times greater than the precision of δ 18 O measurements of most laboratories. No change in 13 C content was observed. Increasing the sample size to 100 μmol resulted in an 18 O enrichment of 0.2% and did not affect the 13 C content. Caution needs to be exercised in selecting sample containers for CO 2 isotope-ratio samples of < 200 μmol. If stopcocks are used in construction of containers for such samples, the use of all-glass stopcocks with Apiezon N ® hydrocarbon-based grease will eliminate the fractionation of oxygen isotopes.

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Kinga M. Revesz, Tyler B. Coplen. 1991. Caution on the use of Viton® or FETFE® O-rings in carbon dioxide sample containers for δ 18 0 analysis. https://doi.org/10.1016/0168-9622(91)90054-z

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