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On‐line Reduction of H 2 O for δ 2 H and δ 18 O Measurement by Continuous‐flow Isotope Ratio Mass Spectrometry
Author(s) -
Begley Ian S.,
Scrimgeour Charles M.
Publication year - 1996
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/(sici)1097-0231(19960610)10:8<969::aid-rcm532>3.0.co;2-o
Subject(s) - chemistry , isotope ratio mass spectrometry , mass spectrometry , analytical chemistry (journal) , nickel , continuous flow , reduction (mathematics) , isotope , stable isotope ratio , δ18o , carbon fibers , line (geometry) , catalysis , chromatography , organic chemistry , mechanics , physics , geometry , mathematics , materials science , quantum mechanics , composite number , composite material
We have evaluated the use of nickel wool, nickelized carbon and a combination of both as catalysts in the on‐line reduction of H 2 O, in a tubular micro‐furnace, for δ 2 H and δ 18 O measurement by continuous‐flow isotope ratio mass spectrometry (CF‐IRMS). The IRMS used was of a novel design which gives adequate resolution to overcome interference from 4 He + on 2 H 1 H + , allowing reduction to be performed in the presence of a He flow. No measurable memory effects were observed for δ 2 H using a nickel catalyst. A small, but significant degree of memory was observed for both δ 2 H and δ 18 O upon combining nickelized carbon and nickel, that was removed by two washes between analyses. On‐line reduction is an accurate method of analysis of nL volumes of water, with a precision of ±4‰ for δ 2 H and ±0.4‰ for δ 18 O. The technique is fully adequate for determination of total energy expenditure by the doubly‐labelled water method, being accurate over a wide range of enrichment.