Elemental analyses using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) of geological samples fused with Li2B4O7 and calibrated without matrix-matched standards

Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used as a complementary technique to X-ray fluorescence (XRF), for multi-e lement analysis of geological samples fused with lithium-tetraborate (Li2B4 O7) Different calibration strategies using external non-matrix matched refe rence materials were investigated. Various internal standards were tested, including the use of Li from the flux, and the use of the naturally occurri ng internal standards, Si or Ca. The use of a naturally occurring standard is not as efficient as this required a prior analysis of the samples using XRF The obtained values for the analysis of geological reference materials were compared with consensus literature values, and satisfactory agreement was found. Laser pits, which were formed, had a diameter of 80 mum and 3-5 replicates on each, fused disc were measured. The reproducibility of the me thod was better than 10% for concentrations above 1 mug/g and better than 1 5% for lower concentrations. The use of Li as the internal standard offers the possibility of multielement determinations in geological samples, which have an unknown composition when the laser ablation analysis is carried ou t. However, using the calculated stoichiometric composition of the lithium- tetraborate for the calculation of the Li concentration leads to a constant deviation from the recommended values. Therefore, it was necessary to dete rmine the Li concentration within each sample batch using at least one lith ium tetraborate fused geological reference material. This resulting Li conc entration in the beads was then used for all subsequent samples in a run. L imits of detection, reproducibility, deviation from reference values indica te the potential of LA-ICP-MS for such bulk analysis without matrix matched calibration standards.