| δ(18) O analysis of organic compounds: problems with pyrolysis in molybdenum-lined reactors. | |
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MedLine Citation:
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PMID: 22976207 Owner: NLM Status: In-Data-Review |
Abstract/OtherAbstract:
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RATIONALE: Effective δ(18) O determinations of organic compounds have been made using high-temperature pyrolysis (HTP) units that employ molybdenum (Mo) foil as an oxidation barrier instead of glassy carbon. In this investigation we evaluated the performance of a Mo-lined reactor during δ(18) O determinations from benzoic acid using a standard high-temperature conversion elemental analyser (TC/EA) unit. Our Mo-lined reactor was associated with poor performance statistics. It was hypothesised that this was as a consequence of the partitioning of oxygen within our system. METHODS: In order to test this hypothesis scanning electron microscopy energy-dispersive X-ray spectroscopy (SEM-EDX) and Raman spectroscopy was conducted on two Mo-lined reactors, which had been used for the analysis of benzoic acids. RESULTS: The EDX analysis revealed that the Mo metal, which had become severely pitted and corroded in the region corresponding to the hottest part of the furnace, was associated with Mo-oxide patinas throughout its entire length. CONCLUSIONS: A complex circular reaction between CO, Mo and C is likely to be responsible for the sequestering of a portion of sample oxygen into Mo-oxides, fractionating our sample. Accurate analysis of benzoic acid and other compounds can therefore only be achieved if sample oxygen is quantitatively returned to gaseous CO, preventing the buildup of Mo-oxides within the reactor over time. This is most likely to be achieved if sample gases have a sufficient residence time within the reactive glassy carbon bed, optimising the recovery of sample oxygen. However, such conditions are unlikely to have been met within our standard TC/EA system resulting in poor performance of the Mo-liner compared with other HTP units. Copyright © 2012 John Wiley & Sons, Ltd. |
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Authors:
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Alex Lombino; Tim Atkinson; Steve Firth |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Rapid communications in mass spectrometry : RCM Volume: 26 ISSN: 1097-0231 ISO Abbreviation: Rapid Commun. Mass Spectrom. Publication Date: 2012 Oct |
Date Detail:
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Created Date: 2012-09-14 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8802365 Medline TA: Rapid Commun Mass Spectrom Country: England |
Other Details:
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Languages: eng Pagination: 2407-12 Citation Subset: IM |
Copyright Information:
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Copyright © 2012 John Wiley & Sons, Ltd. |
Affiliation:
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Department of Geography, University College London, Pearson Building, Gower Street, London, WC1E 6BT, UK. ucfaalo@live.ucl.ac.uk. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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