title: Minimization of sample requirement for delta18O in benzoic acid.
abstract: The measurement of the oxygen stable isotope content in organic compounds has applications in many fields, ranging from paleoclimate reconstruction to forensics. Conventional High-Temperature Conversion (HTC) techniques require >20 microg of O for a single delta(18)O measurement. Here we describe a system that converts the CO produced by HTC into CO(2) via reduction within a Ni-furnace. This CO(2) is then concentrated cryogenically, and 'focused' into the isotope ratio mass spectrometry (IRMS) source using a low-flow He carrier gas (6-8 mL/min). We report analyses of benzoic acid (C(7)H(6)O(2)) reference materials that yielded precise delta(18)O measurement down to 1.3 microg of O, suggesting that our system could be used to decrease sample requirement for delta(18)O by more than an order of magnitude.
authors.affiliation: Department of Geology and Geophysics, University of Hawaii, Honolulu, HI 96822, USA.
authors.forename: William M
authors.initials: WM
authors.lastname: Hagopian
authors.forename: A Hope
authors.initials: AH
authors.lastname: Jahren
mesh_terms: D019817:Benzoic Acid / Q000737:chemistry*; D044707:Forensic Sciences / Q000295:instrumentation / Q000379:methods; D006358:Hot Temperature; D013058:Mass Spectrometry / Q000379:methods*; D010103:Oxygen Isotopes / Q000737:chemistry*; D010163:Paleontology / Q000295:instrumentation / Q000379:methods; D012044:Regression Analysis
chemical_list: D010103:Oxygen Isotopes; D019817:Benzoic Acid