Initial measurement of beryllium-9 using high-resolution inductively coupled plasma mass spectrometry allows for more precise applications of the beryllium isotope system within the Earth Sciences.

Abstract

Precise and accurate determination of the ratio of the cosmogenic nuclide 10 Be to the stable isotope 9 Be (10 Be/9 Be) is needed across multiple fields of research within the Earth Sciences. Current techniques used to measure the 9 Be content of geological materials generally require a large amount of sample or solution aliquot and present a large range of analytical precisions. A range of geological reference materials underwent whole-rock dissolution and "strong" (0.04 M NH2 OH.HCl in 25% acetic acid) and "weak" (0.02 M NH2 OH.HCl in 10% acetic acid) leaching to represent a range of potential applications within the geosciences. After treatment, the 9 Be and major element (Na, Ca, Mg, Fe, Mn, Al and Ti) content of sample solutions were determined by high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) using a Thermo® ELEMENT XR instrument. The 9 Be concentration of whole-rock and leaching solutions displayed a wide range of values within each geological reference material, generally following a uniform relationship implying a potential kinetic control on NH2 OH leaching, as suggested by major element profiles. A precision of 0.1 to 1.4% is achieved independent of sample size or leaching strength. Initial results suggest that the use of HR-ICP-MS improves the precision of 9 Be analysis for a range of geological reference materials. A high precision is maintained despite reducing the sample size or strength of leaching solution. This has implications for the use of the Be isotope system within the Earth Sciences by reducing the propagated uncertainty of 10 Be/9 Be ratios or the mass of sample or 9 Be aliquot used.