High-precision laser ablation inductively coupled plasma mass spectrometry determination of trace elements in geological glasses by internal standardization

Abstract

The analysis of trace elements (TE) in geological materials is a valuable tool to understand geological processes, including studies in geochemistry and petrology. Among the methods applied to determine TE, Laser Ablation Inductively Coupled Plasma Mass Spectrometry ­(LA-ICP-MS) detects TE contents in the μg/g and ng/g range. The aim of this paper is to validate, at Laboratório de Geologia Isotópica (LGI) — Centro de Estudos em Petrologia e Geoquímica/Universidade Federal do Rio Grande do Sul (CPGq/UFRGS), a high-precision method for LA-ICP-MS analyses of TE in geological materials. Samples used in this work were reference Max-Planck-Institut für Chemie — Dingwell (MPI-DING) glasses. The method is used in tandem with the Electron Probe Microanalyzer — Wavelength Dispersive X-ray Spectrometer (EPMA-WDS) technique to determine the major and minor elements of the samples and check for homogeneity. Analyses were conducted in a Thermo^® Element2 Inductively Coupled Mass Spectrometer (ICP-MS) coupled to a New Wave Research^® Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) (213nm) laser ablation system. ⁴³Ca and ²⁹Si were used as internal standards (IS). Glitter^® software and in-house spreadsheets were utilized for reduction treatments. The results using ²⁹Si as IS present a high degree of fractionation errors compared to the results using ⁴³Ca. Uncertainties caused by matrix interferences and fractionation effects can be corrected applying a correction factor. The obtained results demonstrate an effective recovery of TE content for the analyzed reference materials. Moreover, these silicate glasses proved to be robust to create an internal database of matrix matching standards in routine silicate analyses.

KEYWORDS:
analytical method; geochemistry; laser ablation inductively coupled plasma mass spectrometer; mass spectrometry; trace elements