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ISOTOPES AND IMPURITIES IN WATER USED FOR WATER TRIPLE POINT CELLS

ISOTOPES AND IMPURITIES IN WATER USED FOR WATER TRIPLE POINT CELLS. EUROMET project 732 WP3: Water Triple Point Cells. WP3: participants and contributors. Participants: Andrea Peruzzi (NMi VSL) Steffen Rudtsch (PTB) Miruna Dobre (SMD) Davor Zvidic (DZM-LPM) Aliye Kartal Dogan (UME)

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ISOTOPES AND IMPURITIES IN WATER USED FOR WATER TRIPLE POINT CELLS

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  1. ISOTOPES AND IMPURITIES IN WATER USED FOR WATER TRIPLE POINT CELLS EUROMET project 732 WP3: Water Triple Point Cells NMi - the Art of Measurement

  2. WP3: participants and contributors Participants: • Andrea Peruzzi (NMi VSL) • Steffen Rudtsch (PTB) • Miruna Dobre (SMD) • Davor Zvidic (DZM-LPM) • Aliye Kartal Dogan (UME) External Contributors: • Harro Meijer (CIO Univ. Groningen) • Detlev Schiel and Reinhard Jaehrling (PTB Braunschweig) • Ken Hill (NRC Ottawa) NMi - the Art of Measurement

  3. Summary • Water triple point cells manufactured at NMi VSL • Isotopes: • Basic definitions to describe isotopic content of water • Isotopic analysis of water samples • Isotopic corrections • Fractionation effects during fabrication process • Temperature differences between the manufactured cells before and after applying the isotopic corrections • Impurities: • ICPMS analysis at PTB • Overall Maximum Estimate (OME) method NMi - the Art of Measurement

  4. Manufactured Water Triple Point Cells • 15 water triple point cells manufactured • Borosilicate vs quartz • HF vs HNO3 • What is the difference between high-silica glass, fused quartz glass, fused silica glass? NMi - the Art of Measurement

  5. Expressing the isotopiccomposition • Natural water is a mixture of the following 4 isotopologues: 1H216O 1H217O 1H218O 2H216O • The triple point temperature of any sample of natural water depends on the relative concentrations of the 4 isotopologues • Ttp = 273.16 K only for Vienna Standard Mean Ocean Water (VSMOW) : • In practice, the water contained in a WTPC always deviates from VSMOW. • The isotopic composition of a sample of natural water is described in terms of its departure from VSMOW (delta-values): NMi - the Art of Measurement

  6. Isotopic content of WTPCs • Samples taken at different stages while fabricating the cell • Isotopic analysis of samples performed by CIO (Univ. Groningen) • d 18O and d 2H measured for each sample Receiver water Starting water Bulb water u( 18O) =  0.08 permil (k=1) u( 2H) =  0.8 permil (K=1) NMi - the Art of Measurement

  7. WTPC water and Global Meteoric Water line For precipitation water: d2H = 8d18O + 10 (GMWL in permil) NMi - the Art of Measurement

  8. Agreement between different labs Hart Scientific cell: CIO analysis: d18O = (-0.93  0.12) permil d2H = (-2.1  2.0) permil Utah Univ. analysis: d18O = (-0.6  0.21) permil d2H = (-3.0  6.0) permil (K = 2) (K = 2) Isotech cell: CIO analysis: d18O = (2.02  0.14) permil d2H = (4.9  2.0) permil Isotech analysis: d18O = (1.10  0.21) permil d2H = (6.09  6.0) permil NMi - the Art of Measurement

  9. Applying isotopic corrections 17O estimated from relation: (Meijer, 1998) NMi - the Art of Measurement

  10. Isotope fractionation UHP water Filtered tap water • Double distillation globally depletes the water (about 20 K) • Degassing enriches the water (only 1-2 K) • UHP water is preferable to filtered tap water NMi - the Art of Measurement

  11. Realized triple point temperatures (K = 1) • Blue: no correction applied • Red: isotopic correction applied NMi - the Art of Measurement

  12. IMPURITIES (CHEMICAL ANALYSIS) • ICPMS at NMi VSL, PTB and NRC (to investigate level of agreement between different labs) • Analysis performed on starting, receiver and bulb water (to investigate contaminations from fabrication process) NMi - the Art of Measurement

  13. ICPMS ANALYSIS RESULTS (PTB) • Concentration (mass fraction in pg/g) for 60 to 70 elemental impurities • Mass fraction converted into molar fraction (mol/mol) NMi - the Art of Measurement

  14. OME (Overall Maximum Estimate) • Depending on the cell: • Correction not applied NMi - the Art of Measurement

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