Analytical Sciences

Abstract − Analytical Sciences, 34(6), 667 (2018).

A Rapid and Precise Determination of Boron Isotope Ratio in Water and Carbonate Samples by Multiple Collector ICP-MS
Masaharu TANIMIZU,*,** Kazuya NAGAISHI,*** and Tsuyoshi ISHIKAWA**
*Department of Chemistry for Environment, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan
**Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, 200 Monobe-Otsu, Nankoku 783-8502, Japan
***Marine Works Japan Ltd., 200 Monobe-Otsu, Nankoku 783-8502, Japan
We developed a method for rapid and precise determination of B isotope ratios by MC-ICP-MS through an optimization of washout method, mass-discrimination correction and chemical separation. Resultant reproducibility of δ11B values was ±0.4‰ (2 × SD) when a simple standard-sample bracketing technique was used, and it was improved to be better than ±0.2‰ by a mass discrimination correction with a 7Li/6Li isotopic reference. A mixed solution, which consists of HNO3–HF–mannitol, allowed a rapid washout of B memory in the sample introduction line. The validation of this technique to a wide range of δ11B value and various B signal intensities was confirmed from a series of B reference solutions with δ11B values of –20 to +40‰ and 25 to 125 ng/g B. Analyses of seawater standard (BCR-403) and carbonate standard (JCp-1) with sample sizes of less than 50 ng B gave δ11B values consistent with those determined by TIMS as Cs2BO2+. The simple and high-precision technique developed here is applicable to various types of commercially supplied multiple collector ICP mass spectrometers without any modification of the sample introduction system from their original instrumental setting.