A new high‐quality set of singly (²H) and doubly (²H and ¹⁸O) stable isotope labeled reference waters for biomedical and other isotope‐labeled research

Abstract

RATIONALE:Research using water with enriched levels of the rare stable isotopes of hydrogen and/or oxygen requires well-characterized enriched reference waters. The International Atomic Energy Agency (IAEA) did have such reference waters available, but these are now exhausted. New reference waters thus had to be produced in sufficient quantity, and higher characterization quality was desired. METHODS: The reference waters have been prepared gravimetrically from three parent waters: natural water, pure 2 H water and highly 18 O-enriched water. These parent waters have been thoroughly assessed for their full isotopic compositions. To ensure the integrity and correctness of the gravimetric procedure, validation measurements have been carried out on the isotopic composition of the produced reference waters by two of our laboratories. These measurements corroborate the values obtained on the basis of gravimetric data. RESULTS: Two new sets of three reference waters enriched in the stable isotopes have been produced and certified: one set of singly labeled waters, only enriched in 2 H, and another set of Doubly Labeled Waters, enriched in both 2 H and 18 O. They cover δ 2 H and δ 18 O values in the range of 800-16000 ‰ and 100-2000 ‰, respectively. The process has led to highly accurate isotopic values for these waters. CONCLUSIONS: These reference waters are now available (called IAEA-604 to IAEA-609). They will be valuable as reference materials for all fields using isotope labeling of water, most prominently, but not exclusively, biomedical research (body composition analyses, metabolic rate measurements). The two waters with the lowest enrichments will also be useful as anchor values for isotope measurements around the natural range. © 2015 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons Ltd.Analysis of the stable isotope ratios of hydrogen and oxygen has widespread applications in a variety of sciences, such as atmospheric research, [1,2] hydrology, [3,4] (paleo) climatology, [5][6][7][8] and medicine and biology. An example of the latter is the application of stable isotopes in water as tracers to assess the water fraction of the total body mass, [9][10][11] and the energy expenditure of humans and animals. [12][13][14] Both methods have a non-destructive, nonrestrictive character: a small portion of water labeled with one or both stable isotopes must be administered to the person or the animal, and one (singly labeled) or two (doubly labeled) samples of one of the possible body fluids (saliva, blood, urine) must be taken. The way in which the singly labeled method establishes the total amount of body water (and thus produces valuable information about body composition) is straightforward: it is based on the dilution of the original administered isotope label by the total body water. Provided that the administered amount and the enrichments of the labeled water are well known, the labeled water has been fully equilibrated through the body, and the final isotope measurement i...

A thoroughly validated spreadsheet for calculating isotopic abundances (2H, 17O, 18O) for mixtures of waters with different isotopic compositions

“…The immediate cause for developing and thoroughly testing this spreadsheet was our recent production of a new series of stable isotope labeled reference waters from gravimetric mixing of natural water with pure 2 H and highly 18 O-enriched waters. [29] For this work, many, and sometimes iterative, calculations of the isotope values of mixtures had to be performed, and we developed the present spreadsheet as a versatile tool for this work. As it is Excel-based, it can also easily be incorporated into larger Excel calculation structures, which was indispensible for the work presented in Faghihi et al [29] The isotopic values of both the pure 2 H water and the highly 18 O-enriched water were not accurately known from certifications, and were not specified at all for the non-enriched isotopes.…”

“…[29] For this work, many, and sometimes iterative, calculations of the isotope values of mixtures had to be performed, and we developed the present spreadsheet as a versatile tool for this work. As it is Excel-based, it can also easily be incorporated into larger Excel calculation structures, which was indispensible for the work presented in Faghihi et al [29] The isotopic values of both the pure 2 H water and the highly 18 O-enriched water were not accurately known from certifications, and were not specified at all for the non-enriched isotopes. Figures 1(b) and 1(c) are screenshots of the spreadsheet for this case study.…”

“…This project was a spin-off of the IAEA-funded project (contract NET-17151) for the production of new isotopeenriched reference waters. [29] V. Faghihi would like to acknowledge the support of the Iranian Ministry of Science, Research and Technology.…”

Optimization of on‐line hydrogen stable isotope ratio measurements of halogen‐ and sulfur‐bearing organic compounds using elemental analyzer–chromium/high‐temperature conversion isotope ratio mass spectrometry (EA‐Cr/HTC‐IRMS)

“…Internationally distributed isotopic reference waters VSMOW, VSMOW2, SLAP, SLAP2 and GISP were used for normalization of the VSMOW‐SLAP isotope‐delta scales. In addition, 2 H‐enriched reference waters IAEA‐604, UC04 and USGS W‐89262, as well as polyethylene IAEA‐CH‐7, were used for validation. Chemicals such as iodomethane, cis ‐dichloroethylene, and trichloroethylene were provided in sealed glass ampoules from stocks at Indiana University (Bloomington, IN, USA) .…”

Measurement of extremely 2H‐enriched water samples by laser spectrometry: application to batch electrolytic concentration of environmental tritium samples

“…In 2015, the International Atomic Energy Agency (IAEA, Vienna, Austria) announced new 2 H-(and 18 O-) enriched primary HDO standards. [21] For the purposes of tritium enrichment, two of these standards (IAEA605, IAEA606) were useful for the development of 2 H-enriched laboratory calibration standards. The δ 2 H VSMOW-SLAP values of the IAEA primary reference waters are summarized in Table 1.…”