title: Development of laser ablation multi-collector inductively coupled plasma mass spectrometry for boron isotopic measurement in marine biocarbonates: new improvements and application to a modern Porites coral.
abstract: BACKGROUND
  Laser Ablation coupled to Multi-Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICPMS) is a powerful tool for the high-precision measurement of the isotopic ratios of many elements in geological samples, with the isotope ratio ((11) B/(10) B) of boron being used as an indicator of the pH of oceanic waters. Most geological samples or standards are polished and ablation occurs on flat surfaces. However, the shape and the irregularities of marine biocarbonates (e.g., corals, foraminifera) can make precise isotopic measurements of boron difficult. Even after polishing, the porosity properties and the presence of holes or micro-fractures affect the signal and the isotopic ratio when ablating the material, especially in raster mode.
  
  
  METHODS
  The effect of porosity and of the crater itself on the (11) B signal and the isotopic ratio acquired by LA-MC-ICPMS in both raster and spot mode was studied. Characterization of the craters was then performed with an optical profilometer to determine their shapes and depths. Surface state effects were examined by analyzing the isotopic fractionation of boron in silicate (NIST-SRM 612 and 610 standards) and in carbonate (corals).
  
  
  RESULTS
  Surface irregularities led to a considerable loss of signal when the crater depth exceeded 20 µm. The stability and precision were degraded when ablation occurred in a deep cavity. The effect of laser focusing and of blank correction was also highlighted and our observations indicate that the accuracy of the boron isotopic ratio does not depend on the shape of the surface. After validation of the analytical protocol for boron isotopes, a raster application on a Porites coral, which grew for 18 months in an aquarium after field sampling, was carried out.
  
  
  CONCLUSIONS
  This original LA-MC-ICPMS study revealed a well-marked boron isotope ratio temporal variability, probably related to growth rate and density changes, irrespective of the pH of the surrounding seawater. Copyright © 2015 John Wiley & Sons, Ltd.
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement (LSCE/IPSL, UMR 8212 CNRS CEA-UVSQ), 91198, Gif-sur-Yvette Cedex, France.
authors.forename: François
authors.initials: F
authors.lastname: Thil
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement (LSCE/IPSL, UMR 8212 CNRS CEA-UVSQ), 91198, Gif-sur-Yvette Cedex, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Blamart
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement (LSCE/IPSL, UMR 8212 CNRS CEA-UVSQ), 91198, Gif-sur-Yvette Cedex, France.|IRD-Sorbonne Universités (UPMC, Univ. Paris 06)-CNRS-MNHN, LOCEAN Laboratory, IRD France-Nord, 32, avenue Henri Varagnat, F-93143, Bondy, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Assailly
authors.affiliation: IRD-Sorbonne Universités (UPMC, Univ. Paris 06)-CNRS-MNHN, LOCEAN Laboratory, IRD France-Nord, 32, avenue Henri Varagnat, F-93143, Bondy, France.
authors.forename: Claire E
authors.initials: CE
authors.lastname: Lazareth
authors.affiliation: Group of Electrical Engineering, Paris (CNRS, Centrale Supelec, Paris-Sud, UPMC), 11 rue Joliot Curie, Plateau de Moulon, 91192, Gif sur Yvette Cedex, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Leblanc
authors.affiliation: IRD-Sorbonne Universités (UPMC, Univ. Paris 06)-CNRS-MNHN, LOCEAN Laboratory, IRD France-Nord, 32, avenue Henri Varagnat, F-93143, Bondy, France.
authors.forename: John
authors.initials: J
authors.lastname: Butsher
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement (LSCE/IPSL, UMR 8212 CNRS CEA-UVSQ), 91198, Gif-sur-Yvette Cedex, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Douville
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000737:chemistry*; D001895:Boron / Q000032:analysis*; D002254:Carbonates / Q000032:analysis*; D007554:Isotopes / Q000032:analysis*; D053685:Laser Therapy; D013058:Mass Spectrometry / Q000295:instrumentation / Q000379:methods*
chemical_list: D002254:Carbonates; D007554:Isotopes; D001895:Boron