Rapid 18O analysis of small water and CO2 samples using a continuous-flow isotope ratio mass spectrometer.
High-frequency throughput is often needed in isotopic studies in biological and medical fields. Here we report that high-precision oxygen isotope ratio measurements of water (+/-0.13 per thousand) were rapidly and routinely made on small samples (40-100 microL) using an isotope ratio mass spectrometer operated in continuous-flow mode. Simple modifications to existing instrumentation allow for rapid manual analyses of dilute CO2 (10% CO2/90% N2), including the addition of a septum port and water trap prior to the gas chromatography (GC) column (elemental analyzer column in this study) and the extension of fused-silica capillary tubing between the mass spectrometer source and the effluent tubing from the GC column (located within the CONFLO unit on Finnigan mass spectrometers). We routinely analyzed 20 small-volume samples per hour using this technique, without sacrificing precision of the oxygen isotope ratio measurement.
Fessenden
Julianna E
JE
Stable Isotope Ratio Facility for Environmental Research, Department of Biology, University of Utah, 257 S. 1400 E., Salt Lake City, UT 84112, USA. fessenden@gps.caltech.edu
Cook
Craig S
CS
Lott
Michael J
MJ
Ehleringer
James R
JR
D002245:Carbon Dioxide / Q000737:chemistry*; D005618:Fresh Water / Q000737:chemistry*; D013058:Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D010103:Oxygen Isotopes / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D010103:Oxygen Isotopes; D002245:Carbon Dioxide