title: Oxygen isotope corrections for online delta(34)S analysis.
abstract: Elemental analyzers have been successfully coupled to stable-isotope-ratio mass spectrometers for online measurements of the delta(34)S isotopic composition of plants, animals and soils. We found that the online technology for automated delta(34)S isotopic determinations did not yield reproducible oxygen isotopic compositions in the SO(2) produced, and as a result calculated delta(34)S values were often 1-3 per thousand too high versus their correct values, particularly for plant and animal samples with high C/S ratio. Here we provide empirical and analytical methods for correcting the S isotope values for oxygen isotope variations, and further detail a new SO(2)-SiO(2) buffering method that minimizes detrimental oxygen isotope variations in SO(2).
authors.affiliation: Institute of Pacific Islands Forestry, USDA Forest Service, 1151 Punchbowl St., Room 323, Honolulu, HI 96813, USA. brianfry@fs.fed.us
authors.forename: Brian
authors.initials: B
authors.lastname: Fry
authors.forename: Steven R
authors.initials: SR
authors.lastname: Silva
authors.forename: Carol
authors.initials: C
authors.lastname: Kendall
authors.forename: Richard K
authors.initials: RK
authors.lastname: Anderson
mesh_terms: D000818:Animals; D019411:Clinical Laboratory Techniques / Q000592:standards*; D013058:Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D010103:Oxygen Isotopes / Q000032:analysis*; D010944:Plants / Q000737:chemistry; D012987:Soil / Q000032:analysis; D013460:Sulfur Isotopes / Q000032:analysis*
chemical_list: D010103:Oxygen Isotopes; D012987:Soil; D013460:Sulfur Isotopes