title: High-precision determination of 18O/16O ratios of silver phosphate by EA-pyrolysis-IRMS continuous flow technique.
abstract: A high-precision, and rapid on-line method for oxygen isotope analysis of silver phosphate is presented. The technique uses high-temperature elemental analyzer (EA)-pyrolysis interfaced in continuous flow (CF) mode to an isotopic ratio mass spectrometer (IRMS). Calibration curves were generated by synthesizing silver phosphate with a 13 per thousand spread in delta(18)O values. Calibration materials were obtained by reacting dissolved potassium dihydrogen phosphate (KH(2)PO(4)) with water samples of various oxygen isotope compositions at 373 K. Validity of the method was tested by comparing the on-line results with those obtained by classical off-line sample preparation and dual inlet isotope measurement. In addition, silver phosphate precipitates were prepared from a collection of biogenic apatites with known delta(18)O values ranging from 12.8 to 29.9 per thousand (V-SMOW). Reproducibility of +/- 0.2 per thousand was obtained by the EA-Py-CF-IRMS method for sample sizes in the range 400-500 microg. Both natural and synthetic samples are remarkably well correlated with conventional (18)O/(16)O determinations. Silver phosphate is a very stable material and easy to degas and, thus, could be considered as a good candidate to become a reference material for the determination of (18)O/(16)O ratios of phosphate by high-temperature pyrolysis.
authors.affiliation: Laboratoire CNRS UMR 5125 Paléoenvironnements & Paléobiosphère, Université Claude Bernard Lyon 1, Campus de la Doua, F-69622, Villeurbanne, France. clecuyer@univ-lyon1.fr
authors.forename: Christophe
authors.initials: C
authors.lastname: Lécuyer
authors.forename: François
authors.initials: F
authors.lastname: Fourel
authors.forename: François
authors.initials: F
authors.lastname: Martineau
authors.forename: Romain
authors.initials: R
authors.lastname: Amiot
authors.forename: Aurélien
authors.initials: A
authors.lastname: Bernard
authors.forename: Valérie
authors.initials: V
authors.lastname: Daux
authors.forename: Gilles
authors.initials: G
authors.lastname: Escarguel
authors.forename: John
authors.initials: J
authors.lastname: Morrison
mesh_terms: D000818:Animals; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D010103:Oxygen Isotopes / Q000737:chemistry*; D010710:Phosphates / Q000032:analysis* / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry; D018030:Silver Compounds / Q000032:analysis* / Q000737:chemistry; D014070:Tooth / Q000737:chemistry*
chemical_list: D010103:Oxygen Isotopes; D010710:Phosphates; D017680:Potassium Compounds; D018030:Silver Compounds; C013216:potassium phosphate; C039072:silver phosphate