Lithium isotope analysis of natural and synthetic glass by laser ablationMC-ICP-MS

Abstract

This contribution presents the first laser ablation multicollector ICP-MS (LA-MC-ICP-MS) technique for the measurement of Li isotopes. A Nu Instruments NuPlasma HR operating at 6 kV and fitted with a non-standard “low-mass, high abundance” skimmer cone is used, coupled to a NewWave UP213 213 nm laser ablation unit operating under a He atmosphere. Asymmetric tuning of the quad lenses on the NuPlasma allows the simultaneous measurement of ⁷Li and ⁶Li on a Faraday-ion counter configuration. Use of the standard-bracketing technique for analysis of unknowns obviates any cross calibration between Faraday cup and ion counter. Use of a natural glass as bracketing standard (e.g. BCR-2G) yields accurate Li isotope data with external, measured 2σ δ⁷Li precision of <1‰ at Li concentrations of 3–35 ppm.