Evaluation of the performance of high temperature conversion reactors for compound-specific oxygen stable isotope analysis.
In this study conversion conditions for oxygen gas chromatography high temperature conversion (HTC) isotope ratio mass spectrometry (IRMS) are characterised using qualitative mass spectrometry (IonTrap). It is shown that physical and chemical properties of a given reactor design impact HTC and thus the ability to accurately measure oxygen isotope ratios. Commercially available and custom-built tube-in-tube reactors were used to elucidate (i) by-product formation (carbon dioxide, water, small organic molecules), (ii) 2nd sources of oxygen (leakage, metal oxides, ceramic material), and (iii) required reactor conditions (conditioning, reduction, stability). The suitability of the available HTC approach for compound-specific isotope analysis of oxygen in volatile organic molecules like methyl tert-butyl ether is assessed. Main problems impeding accurate analysis are non-quantitative HTC and significant carbon dioxide by-product formation. An evaluation strategy combining mass spectrometric analysis of HTC products and IRMS18O/16O monitoring for future method development is proposed.
a Department of Isotope Biogeochemistry , Helmholtz-Centre for Environmental Research - UFZ , Leipzig , Germany.
Kristina L
KL
Hitzfeld
a Department of Isotope Biogeochemistry , Helmholtz-Centre for Environmental Research - UFZ , Leipzig , Germany.
Matthias
M
Gehre
a Department of Isotope Biogeochemistry , Helmholtz-Centre for Environmental Research - UFZ , Leipzig , Germany.
Hans-Hermann
HH
Richnow
D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry; D006358:Hot Temperature; D008738:Methyl Ethers / Q000032:analysis; D010103:Oxygen Isotopes / Q000032:analysis
D008738:Methyl Ethers; D010103:Oxygen Isotopes; C043243:methyl tert-butyl ether
Carbon monoxide; GC-HTC-IRMS; compound-specific isotope analysis; high temperature conversion; isotope measurement; isotope ratio; oxygen-18