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...

RATIONALE: Oxygen and hydrogen stable isotopes are widely used tracers for studies on naturally occurring and laboratory mixtures of isotopically different waters. Although the mixing calculations are straightforward to perform, there are ample possibilities to make mistakes, especially when dealing with a large number of mixed fluids. To facilitate isotope mixing calculations and to avoid computational mistakes, a flexible tool to carry out these calculations is in demand. METHODS: We developed, in three independent efforts, spreadsheets to carry out the mixing calculations for a combination of waters with different isotopic compositions using the isotope mass balance equation. We validated our calculations by comparison of the results of the three spreadsheets for a large number of test calculations. For all the cases, we obtained identical results down to the 12 th to 14 th significant digit. RESULTS: We present a user-friendly, thoroughly validated spreadsheet for calculating 2 H, 17 O and 18 O stable isotopic abundances and respective isotope delta values for mixtures of waters with arbitrary isotopic compositions. The spreadsheet allows the mixing of up to 10 different waters, of which up to five can be specified using their isotopic abundances and up to five others using their isotope delta values. The spreadsheet is implemented in Microsoft Excel and is freely available from our research groups' websites. CONCLUSIONS: The present tool will be applicable in the production and characterization of singly and doubly labeled water (DLW) mother solutions, the analysis of isotope dilution measurements, the deduction of unknown isotope values of constituents for mixtures of natural waters, and many other applications. Copyright © 2015 John Wiley & Sons, Ltd.Stable isotope mixing calculations are used for studies on naturally occurring interactions between different water bodies: ground water with surface waters (river, lake, stream, wetland, or sea water), [1][2][3][4][5][6] ground water/surface water and precipitation interactions, [7][8][9][10] river and lake/ocean interactions, [11][12][13][14][15] and in addition, in laboratory applications such as the use of the isotope dilution technique, and the production of enriched and diluted mixtures for pharmaceutical and biological studies. [16][17][18][19][20] Isotopic compositions mix conservatively. The isotopic abundances of a mixture are simply related to the isotopic abundances of the isotopes in each component and the mole fraction of the individual components. While the calculations seem straightforward to perform using simple expressions, they are nevertheless complicated, with ample possibilities of making mistakes. This is especially the case when dealing with the mixing of waters of which some are specified with their isotopic abundances and others with delta values. Also, the calculations become more complex when the number of mixed fluids increases. To facilitate isotope mixing calculations and to avoid computational mistakes, we developed a flexible ...

Variation in the isotopic composition of water is one of the major contributors to uncertainty in the realization of the triple point of water (TPW). Although the dependence of the TPW on the isotopic composition of the water has been known for years, there is still a lack of a detailed and accurate experimental determination of the values for the correction constants. This paper is the first of two articles (Part I and Part II) that address quantification of isotope abundance effects on the triple point temperature of water. In this paper, we describe our experimental assessment of the 2 H isotope effect. We manufactured five triple point cells with prepared water mixtures with a range of 2 H isotopic abundances encompassing widely the natural abundance range, while the 18 O and 17 O isotopic abundance were kept approximately constant and the 18 O − 17 O ratio was close to the Meijer-Li relationship for natural waters. The selected range of 2 H isotopic abundances led to cells that realised TPW temperatures between approximately −140 μK to +2500 μK with respect to the TPW temperature as realized by VSMOW (Vienna Standard Mean Ocean Water). Our experiment led to determination of the value for the δ 2 H correction parameter of A 2H = 673 μK / (‰ deviation of δ 2 H from VSMOW) with a combined uncertainty of 4 μK (k = 1, or 1σ).