Adaptation of the Unterzaucher procedure for determination of oxygen-18 in organic substances

Santrock, Jeffrey; Hayes, John M.

doi:10.1021/ac00128a025

Cited by 52 publications

(31 citation statements)

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“…Water samples have been analyzed using a modified gas chromatography -combustion (GC-C) system; 26 a laser technique for the analysis of carbonates and phosphates 27 was described, and for the conversion of organic substances modified elemental analyser -isotope ratio mass spectrometry (EA-IRMS) systems [28][29][30][31][32] are used. Systems allowing the GC separation and on-line pyrolytic conversion of volatile samples also exist.…”

Section: Conversion Methodsmentioning

confidence: 99%

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Standardization for oxygen isotope ratio measurement - still an unsolved problem

Kornexl¹,

Werner

Gehre³

1999

Rapid Commun. Mass Spectrom.

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Numerous organic and inorganic laboratory standards were gathered from nine European and North American laboratories and were analyzed for their delta(18)O values with a new on-line high temperature pyrolysis system that was calibrated using Vienna standard mean ocean water (VSMOW) and standard light Antartic precipitation (SLAP) internationally distributed reference water samples. Especially for organic materials, discrepancies between reported and measured values were high, ranging up to 2 per thousand. The reasons for these discrepancies are discussed and the need for an exact and reliable calibration of existing reference materials, as well as for the establishment of additional organic and inorganic reference materials is stressed. Copyright 1999 John Wiley & Sons, Ltd.

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Section: Conversion Methodsmentioning

confidence: 99%

“…28). It is important to note that most of the above methods (especially the conventional off-line techniques) have a limited applicability to one or sometimes to a few chemical compounds; in general, they cannot be used to convert a large variety of chemical species or mixtures thereof.…”

Section: Conversion Methodsmentioning

confidence: 99%

Standardization for oxygen isotope ratio measurement - still an unsolved problem

Kornexl¹,

Werner

Gehre³

1999

Rapid Commun. Mass Spectrom.

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“…Samples from Inuit groups suggest that humans with marine-dominated diets can be identified on the basis of coupled (Estep and Dabrowski, 1980), but the interpretation of hydrogen isotope data from complex organic tissues quickly became clouded as it was recognized that a significant fraction of the H atoms in these tissues were subject to continuous exchange with ambient water and water vapor (DeNiro and Epstein, 1981;Schimmelmann et al, 1993). The reluctance to pursue organic oxygen in part reflects analytical challenges (Santrock and Hayes, 1987) However, the majority of the isotopic signal in animal tissues, at least for H in proteinaceous tissues of humans, is derived from diet and not inherited directly from water (Sharp et al, 2003). Isotopic variation related to dietary composition represents a potentially confounding factor in the use of H and O isotopes for geographic tracking, but also a potential signal of interest for dietary research.…”

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confidence: 99%

Dietary and physiological controls on the hydrogen and oxygen isotope ratios of hair from mid‐20th century indigenous populations

Bowen

Ehleringer

Chesson

et al. 2009

American J Phys Anthropol

121

150

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A semimechanistic model has recently been proposed to explain observed correlations between the H and O isotopic composition of hair from modern residents of the USA and the isotopic composition of drinking water, but the applicability of this model to hair from non-USA and preglobalization populations is unknown. Here we test the model against data from hair samples collected during the 1930s-1950s from populations of five continents. Although C and N isotopes confirm that the samples represent a much larger range of dietary "space" than the modern USA residents, the model is able to reproduce the observed delta(2)H and delta(18)O values given reasonable adjustments to 2 model parameters: the fraction of dietary intake derived from locally produced foods and the fraction of keratin H fixed during the in vivo synthesis of amino acids. The model is most sensitive to the local dietary intake, which appears to constitute between 60% and 80% of diet among the groups sampled. The isotopic data are consistent with a trophic-level effect on protein H isotopes, which we suggest primarily reflects mixing of (2)H-enriched water and (2)H-depleted food H in the body rather than fractionation during biosynthesis. Samples from Inuit groups suggest that humans with marine-dominated diets can be identified on the basis of coupled delta(2)H and delta(18)O values of hair. These results indicate a dual role for H and O isotopic measurements of keratin, including both biological (diet, physiology) and environmental (geographic movement, paleoclimate) reconstruction.

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“…The Schutze-Unterzaucher procedure is well established as a technique for oxygen elemental analysis [1][2][3][4][5] and, more recently, for isotope analysis. 6 The sample is pyrolysed over nickelized carbon at 1060 °C to convert all oxygen products to carbon monoxide, which is then oxidized to CO 2 with iodine pentoxide. As well as correcting for any contamination of the oxygen pool in CO 2 by an oxygen blank (associated with the cups used for containing the sample for pyrolysis) and memory (oxygen from previous samples), it is necessary to correct for the oxygen contributed by iodine pentoxide to the CO 2 .…”

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confidence: 99%

A rapid on-line technique for determination of oxygen isotope composition of nitrogen-containing organic matter and water

Farquhar

Henry

Styles

1997

Rapid Commun. Mass Spectrom.

144

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A rapid, inexpensive on-line technique for the analysis of stable isotopes of oxygen in organic matter and water is described. The oxygen in the sample is pyrolysed over nickelized carbon using a modified Unterzaucher technique and converted to carbon monoxide. Separation of the CO from N 2 by gas chromatography before mass spectrometric measurement of the 18 O/ 16 O ratio allows application of the technique to nitrogen containing samples. The precision of measurements is generally as good as, or better than, that obtained with other methods (σ = 0.2‰ for n = 10). A major advantage of the method is its speed, each sample taking less than 7 minutes to analyse. The technique improves on those used previously, in being applicable to a wide range of samples including N-containing organic matter and water and in being rapid, simple and inexpensive while retaining precision. © 1997 by John Wiley & Sons, Ltd. Received 21 May 1997; Accepted 22 July 1997 Rapid. Commun. Mass Spectrom. 11, 1554-1560(1997 Effective and reliable analysis of stable isotopes of oxygen in organic matter and in water has become an attractive goal in recent years. Oxygen isotope analysis has many applications related to ecology (sources of water, seasonality of growth), agriculture (screen for stomatal conductance), physiology/biochemistry (water pathways, kinetic limitations), climate reconstruction (tree rings), forensic science (origins of drugs, paper, cotton, wine, etc.) and global climate change (sinks and sources of CO 2 ). Whilst rapid, accurate techniques are well established for measurement of stable isotopes of other biologically important elements (carbon, hydrogen and nitrogen), studies employing 18 O have been hampered by the lack of a rapid, generally applicable analytical technique. This paper describes a rapid, inexpensive on-line method for measuring the oxygen isotope ratio of organic and water samples.Traditionally, analysis of oxygen isotopes has involved decomposition of the sample by pyrolysis and conversion of the oxygen-containing products to carbon dioxide. The focus has been on CO 2 as the target gas because it is readily formed by chemical action and is easy to trap and purify. The Schutze-Unterzaucher procedure is well established as a technique for oxygen elemental analysis [1][2][3][4][5] and, more recently, for isotope analysis. 6 The sample is pyrolysed over nickelized carbon at 1060 °C to convert all oxygen products to carbon monoxide, which is then oxidized to CO 2 with iodine pentoxide. As well as correcting for any contamination of the oxygen pool in CO 2 by an oxygen blank (associated with the cups used for containing the sample for pyrolysis) and memory (oxygen from previous samples), it is necessary to correct for the oxygen contributed by iodine pentoxide to the CO 2 .Other methods used include those of Rittenberg and Ponticorvo 7 and Thompson and Gray. 8 The first, involving pyrolysing the sample in the presence of mercuric chloride at around 500 °C, has been improved more recently by Schimmelmann and De...

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Adaptation of the Unterzaucher procedure for determination of oxygen-18 in organic substances

Cited by 52 publications

References 31 publications

Standardization for oxygen isotope ratio measurement - still an unsolved problem

Standardization for oxygen isotope ratio measurement - still an unsolved problem

Dietary and physiological controls on the hydrogen and oxygen isotope ratios of hair from mid‐20th century indigenous populations

A rapid on-line technique for determination of oxygen isotope composition of nitrogen-containing organic matter and water

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