Oxygen Isotope Analyses of Biogenic Opal and Quartz using a novel Microfluorination Technique

Anthony J. Menicucci, Joy A. Matthews, Howard J. Spero

Research output: Contribution to journalArticlepeer-review

Abstract

<p> Rationale: Measuring &delta; <sup> 18 </sup> O values in silicates is difficult and hazardous in comparison with measurements of carbonate minerals due to the difficulty in breaking Si&ndash;O&ndash;Si bonds. A novel method for measurement of &delta; <sup> 18 </sup> O values from quartz and biogenic silica utilizing high&hyphen;temperature pyrolysis with continuous&hyphen;flow isotope ratio mass spectrometry (CF&hyphen;IRMS) is presented.</p><p> Methods: Samples were prepared by offline dehydroxylation/dehydration under vacuum at 1060&deg;C. The dehydroxylated samples are mixed with polytetrafluoroethylene (PTFE) powder (2.3:1 PTFE/Si) and graphite in silver foil capsules and reacted in a vario PYRO cube TC/EA system in a glassy carbon reaction tube. Quartz and biogenic opal samples react with available carbon in a microfluorination environment upon decomposition of the PTFE, producing CO for analysis via CF&hyphen;IRMS.</p><p> Results: Silicate samples reacted quantitatively, producing data with yields &ge;88% from ~400&thinsp;&micro;g samples. Multiple analyses with international standards demonstrated accuracy for replicate measurements (1&sigma; range &plusmn;0.3&ndash;0.6&permil;), comparing favorably with previously published techniques.</p><p> Conclusions: New data produced with the microfluorination technique are comparable with data from studies using existing methodologies. The microfluorination technique has the potential to greatly increase the number of laboratories producing silicate oxygen isotope data for mineralogic, paleoclimatic and biogeochemical applications.</p>
Original languageAmerican English
JournalRapid Communications in Mass Spectrometry
Volume27
DOIs
StatePublished - Aug 1 2013
Externally publishedYes

Disciplines

  • Earth Sciences

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