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- Title
An online temperature-controlled vacuum-equilibration preparation system for the measurement of δ2H values of non-exchangeable-H and of δ<sup>18</sup>O values in organic materials by isotope-ratio mass spectrometry.
- Authors
Wassenaar, Leonard I.; Hobson, Keith A.; Sisti, Leonardo
- Abstract
RATIONALE: Measurement of δ2H values in non-exchangeable-H (δ2Hn) and δ18O values in organic environmental samples are inconsistent among laboratories worldwide due to varied and lengthy approaches in controlling for H isotope exchange (for δ2Hn values) and removal of trace moisture (δ2Hn and δ18O values), which undermines the comparability of organic δ2H and δ18O data produced among different laboratories. METHODS: An online preparation system was developed for the measurement of the δ2Hn and δ18O values of organic samples, coupled to isotope-ratio mass spectrometers. The system features a 50-position autosampler and isolation valve where (1) the samples are held isothermal between ambient to 40-120 ± 0.1 °C for H isotopic exchange experiments (δ2Hn) and drying of hygroscopic samples (δ2Hn and δ18O), (2) the samples are evacuated to <5 mbar and flushed with helium for moisture and N2 removal, and (3) injection of up to 500 µL of H2O is possible for controlled vapour exchangeable-H experiments. RESULTS: The system provides highly reproducible and precise δ2Hn isotope estimates for a range of organic keratinous standard powders over a wide range of experimental temperatures. A reproducible sample processing regimen can now be applied to a wider range of organics and hygroscopic samples that are currently hampered by poorly controlled preparative methods amongst laboratories. CONCLUSIONS: Rapid and reproducible online vacuum equilibration of samples and standards for the routine measurement of δ2Hn and δ18O values is now possible using the online equilibration system, with the added benefit that sample processing times for organic δ2H values are reduced from weeks to hours.
- Subjects
ISOTOPE exchange reactions; ISOTOPIC analysis; MASS spectrometry; TEMPERATURE control; ORGANIC compounds
- Publication
Rapid Communications in Mass Spectrometry: RCM, 2015, Vol 29, Issue 5, p397
- ISSN
0951-4198
- Publication type
Article
- DOI
10.1002/rcm.7118