Intercomparison of Boron Isotope and Concentration Measurements. Part I: Selection, Preparation and Homogeneity Tests of the Intercomparison Materials

Abstract

In 1999 the Istituto di Geoscienze e Georisorse (IGG), with the support of the International Atomic Energy Agency (IAEA), undertook the collection, preparation and distribution of eight geological materials intended for a blind interlaboratory comparison of measurements of boron isotopic composition and concentration. The materials came from Italian sources and consist of three natural waters (Mediterranean seawater and two groundwaters) and five rocks and minerals (tourmaline, basalt, obsidian, limestone and clay). The solid materials were crushed, milled and mixed, in preparation for distribution. Extensive assays performed at the IGG on these materials demonstrated that their boron isotopic and chemical compositions are homogeneous. Additional homogeneity tests were carried out on solid material fragments at the GeoForschungsZentrum Potsdam, with the specific objective of investigating the suitability of some of them for the calibration in situ of micro‐analytical techniques. Two materials, B4 (tourmaline) and B6 (obsidian), proved to be isotopically homogeneous and may become excellent references for in situ microanalyses of boron isotopes. The materials described here were used as the basis of a major laboratory intercomparison study and are now available for further distribution from either the IAEA (solid materials) or the IGG (waters).

Measurement on high-precision boron isotope of silicate materials by a single column purification method and MC-ICP-MS

“…(2s standard error), which is similar to that of previous works. 9,10,20,21 Some of these rocks, such as B5, B6, B8, JB-2, JB-3 and JR-2, have d 11 B reference values reported in previous studies, and they have also been included in …”

Matrix effects during laser ablation MC ICP-MS analysis of boron isotopes in tourmaline

“…Several analytical technique and inter-laboratory comparisons have been carried out to identify the potential source of analytical uncertainties. Tonarini et al and Gonantini et al 8,17 showed a signicant spread in results and poor agreement between different laboratories. The source of the observed variations in their study was likely related to the specic techniques used for boron extraction and purication or to differences in analytical procedures.…”

“…The sample B4 was used for an inter-laboratory comparison study. 8,17 These four tourmalines represent some of the very best characterised materials for in situ analysis of boron isotopes that are presently available to the geoanalytical community. Four additional samples (EZ-272, JS-82N-1, JS-82A-1A, and EB-67-90) are from the boron isotopic study by Palmer and Slack.…”

“…The utility of boron isotopes in geochemical studies was reviewed by Palmer 11 B/ 10 B ratio usually corresponds to the composition of the NIST SRM 951 boric acid reference material, which has a certied 11 B/ 10 B value of 4.04362 AE 0.00137. 4 Tonarini et al 5 have reviewed various techniques used to measure the isotopic composition of B in natural samples, including positive thermal ionisation mass spectrometry (PTIMS), [6][7][8] negative ion thermal ionisation mass spectrometry (NTIMS), 9,10 inductively coupled plasma mass spectrometry (ICP-MS), 11 multiple-collector ICP-MS (MC ICP-MS), 12 secondary ion mass spectrometry (SIMS or ion probe) 13,14 and laser ablation ICP-MS (LA ICP-MS). 15,16 The analytical uncertainties currently reported for boron isotopic analysis of geological materials vary from 0.2 to 4&.…”

Boron isotope ratio (δ11B) measurements in Water Framework Directive monitoring programs: comparison between double focusing sector field ICP and thermal ionization mass spectrometry

“…Seawater (IAEA-B1) is purified regularly in the same way in order to check for a possible chemical fractionation due to an uncompleted recovery of boron, and to evaluate the accuracy and reproducibility of the overall procedure. [39][40][41] Reproducibility was obtained by repeated measurements of the NBS951, accuracy and reproducibility are controlled with the analysis of the IAEA-B1 seawater standard.…”