Development of an advanced on-line position-specific stable carbon isotope system and application to methyl tert-butyl ether

C. Gauchotte, G. O'Sullivan, Simon Davis, R. Kalin

Research output: Contribution to journalArticle

19 Citations (Scopus)
200 Downloads (Pure)

Abstract

We present an advanced system for on-line position-specific carbon isotope analysis. The main limitation of on-line intramolecular isotope ratio measurements has been that optimal pyrolytic fragments are obtained mostly at temperatures where the analyte has not completely reacted. As a result of undetermined isotopic fractionation, the isotopic signatures of the pyrolysis products are not strictly equal to these of the equivalent moieties in the parent molecule. We designed a pyrolytic unit in which both temperature and reaction time are variable parameters, enabling determination of the enrichment factor of the pyrolysis at optimal temperature by construction of a Rayleigh plot. In the case of methyl tert-butyl ether (MTBE) presented here, a 'pre-pyrolysis' fractionation of MTBE leading to a depletion of 0.9 parts per thousand was discovered and the enrichment factor of the optimal pyrolysis reaction was determined at -1.7 parts per thousand. Absolute delta C-13 values of two functional groups of MTBE - the methoxy group and the 2-methylpropane group - could be determined with 95% confidence intervals of 0.4 parts per thousand and 0.5 parts per thousand, respectively.
Original languageEnglish
Pages (from-to)3183-3193
Number of pages11
JournalRapid Communications in Mass Spectrometry
Volume23
Issue number19
DOIs
Publication statusPublished - 15 Oct 2009

Keywords

  • ratio mass-spectrometry
  • gas-chromatography
  • organic contaminants
  • anaerobic biodegradation
  • aerobic biodegradation
  • hydrogen isotopes
  • fatty-acids
  • fractionation
  • mtbe
  • degradation
  • methyl tert-butyl ether
  • chemistry

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