The contributions of T. B. Coplen, B. Buck, and S. J. Mroczkowski to this article were prepared as part of their official duties as United States Federal Government employees.
Novel silver-tubing method for quantitative introduction of water into high-temperature conversion systems for stable hydrogen and oxygen isotopic measurements
Article first published online: 2 JUN 2010
Copyright © 2010 John Wiley & Sons, Ltd.
Rapid Communications in Mass Spectrometry
Volume 24, Issue 13, pages 1821–1827, 15 July 2010
How to Cite
Qi, H., Gröning, M., Coplen, T. B., Buck, B., Mroczkowski, S. J., Brand, W. A., Geilmann, H. and Gehre, M. (2010), Novel silver-tubing method for quantitative introduction of water into high-temperature conversion systems for stable hydrogen and oxygen isotopic measurements. Rapid Commun. Mass Spectrom., 24: 1821–1827. doi: 10.1002/rcm.4559
- Issue published online: 2 JUN 2010
- Article first published online: 2 JUN 2010
- Manuscript Revised: 26 MAR 2010
- Manuscript Accepted: 26 MAR 2010
- Manuscript Received: 11 JAN 2010
A new method to seal water in silver tubes for use in a TC/EA (thermal conversion/elemental analyzer) reduction unit using a semi-automated sealing apparatus can yield reproducibilities (1 standard deviation) of δ2H and δ18O measurements of 1.0‰ and 0.06‰, respectively. These silver tubes containing reference waters may be preferred for the calibration of H- and O-bearing materials analyzed with a TC/EA reduction unit. The new sealing apparatus employs a computer-controlled stepping motor to produce silver tubes identical in length. The reproducibility of the mass of water sealed in tubes (in a range of 200–400 µg) can be as good as 1%. Approximately 99% of the sealed silver tubes are satisfactory (leak free). Although silver tubes sealed with reference waters are robust and can be shaken or heated to 110°C with no loss of integrity, they should not be frozen because the expansion during the phase transition of water to ice will break the cold seals and all the water will be lost. The tubes should be shipped in insulated containers.
This new method eliminates air inclusions and isotopic fractionation of water associated with the loading of water into capsules using a syringe. The method is also more than an order of magnitude faster than preparing water samples in ordinary Ag capsules. Nevertheless, some laboratories may prefer loading water into silver capsules because expensive equipment is not needed, but users of this method are cautioned to apply the necessary corrections for evaporation, back exchange with laboratory atmospheric moisture, and blanks. Copyright © 2010 John Wiley & Sons, Ltd.