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.
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
Julianna E
JE
Fessenden
Craig S
CS
Cook
Michael J
MJ
Lott
James R
JR
Ehleringer
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