Novel silver‐tubing method for quantitative introduction of water into high‐temperature conversion systems for stable hydrogen and oxygen isotopic measurements

Abstract

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 delta(2)H and delta(18)O measurements of 1.0 per thousand and 0.06 per thousand, 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 microg) 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 degrees 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.

Determinants of blood water δ18O variation in a population of experimental sheep: Implications for paleoclimate reconstruction

“…The dried feed δ 18 O value was measured to be +25.3 ‰ (+/− 0.8 ‰ 1 s.d.). Results were assessed relative to standards IAEA-601 benzoic acid (+23.14 ‰) and IAEA-CH-6 sucrose (house standard for δ 18 O, +36.20 ‰; also referred to as “ANU sucrose”) in addition to USGS encapsulated waters (Qi et al , 2010). The larger scatter for organic δ 18 O values may represent variable contributions of a small amount of residual moisture in the feed to the oxygen intrinsic to organic molecules in the feed.…”

Stable Isotope Analysis of Saline Water Samples on a Cavity Ring-down Spectroscopy Instrument

“…The DI water used for the preparation of each solution had δ 18 O −1.48 ± 0.03‰ and δ 2 H −4.0 ± 0.7‰ as analyzed on the CRDS system (where ±0.03‰ and 0.7‰ are standard deviation of four replicates as in Supporting Information Table S2). The δ-values of DI water were confirmed using a TC/EA method 36 Table S2). Similarly, δ 2 H of MgCl 2 solutions was within a range of ±1.0‰ in relation to DI water δ-value for low concentrations (4.7−9.3 g L −1 ).…”

Caution on the use of NBS 30 biotite for hydrogen-isotope measurements with on-line high-temperature conversion systems

“…Two materials separated from natural rocks in China (CN), muscovite (muscovite‐CN) and biotite (biotite‐CN), might serve as suitable RMs. To determine accurate hydrogen‐isotope compositions of these materials, we relied upon a semi‐automated technique that was published recently and that enables water of any desired δ 2 H value to be sealed in a silver‐tube segment, which can then be loaded into a HTC system . For normalization, water (or any other liquid sealed in a silver‐tube segment) with a known δ 2 H value can be interspersed among solid samples and loaded into the carousel of a HTC system.…”