GGR Handbook of Rock and Mineral Analysis Chapter 12 Laser Ablation-ICP-MS for the In Situ Analysis of Geological Samples

Abstract

This chapter (Laser Ablation-ICP-MS for the In Situ Analysis of Geological Samples) is a contribution to the Geostandards and Geoanalytical Research Handbook of Rock and Mineral Analysis – an online textbook that is a fully revised and updated edition of A Handbook of Silicate Rock Analysis (P. J. Potts, 1987, Blackie, Glasgow).

This Chapter (from Section 3 of the handbook dealing with microbeam analytical techniques) presents an overview of fundamental aspects of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and its application relevant to multi-element measurement and U-Pb dating of geological samples. The chapter describes instrumentation currently used for LA-ICP-MS, physical processes that occur at the ablation site, during aerosol transport and in the ICP, and approaches to quantification of LA-ICP-MS data. Description of laser ablation microprobes focuses on their design aspects that affect analytical performance such as the source of laser light, configuration of the optical path of the laser beam, and the design of the sample cell. Description of ICP-MS instruments focuses on the implications of using single collector mass spectrometers, which are currently the most common type of ICP-MS instruments used for LA-ICP-MS. Description of the tubing connecting laser microprobes to ICP-MS instruments focuses on the impact of its configuration on the uncertainty of LA-ICP-MS measurement results. The description of physical processes includes aspects of the ablation process, digestion of laser ablation aerosol in a dry ICP, and down-hole fractionation during ablation at a fixed location on the sample. Description of approaches to quantification of LA-ICP-MS data covers internal standardisation, calibration of ICP-MS instrument response during analytical runs, matrix effects, use of secondary reference material, interferences and memory effects.