Analytical capabilities of LA-ICP-ToF-MS for ultra-fast 2D quantitative elemental mapping of micrometeorites

Abstract

Time-of-flight ICP-mass spectrometry (ICP-ToF-MS) allows acquisition of almost the entire periodic table in only a few tens of microseconds, with several mass spectra combined into a single readout. When hyphenated with a low-dispersion laser ablation (LA) unit, it allows for 2D elemental mapping at a laser repetition rate of several hundred hertz, with each laser shot recorded as a single pixel. Although its use in geosciences is increasing, the technique is often referred to as semi-quantitative. Here, we present the outcomes of ultra-fast high-resolution 2D mapping and quantification of the constituting elements of geological reference materials and micrometeorites with LA-ICP-ToF-MS, carried out in a period of over a year. Quantitative data for each pixel were obtained through a combination of multi-point external calibration and normalization of the sum of all element oxide contents to 100%. Detection limits ranging from 0.1 to 10 μg g⁻¹ were attained for most elements when using a 5 μm × 5 μm square laser spot. Repeated analysis of reference materials in a period of over one year demonstrates an intermediate precision down to 3% RSD.