High-Speed, High-Resolution, Multielemental LA-ICP-TOFMS Imaging: Part II. Critical Evaluation of Quantitative Three-Dimensional Imaging of Major, Minor, and Trace Elements in Geological Samples

Here we describe the capabilities of laser-ablation coupled to inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOFMS) for high-speed, high-resolution, quantitative three-dimensional (3D) multielemental imaging. The basic operating principles of this instrumental setup and a verification of 3D quantitative elemental imaging are provided. To demonstrate the potential of 3D LA-ICP-TOFMS imaging, high-resolution multielement images of a cesium-infiltrated Opalinus clay rock were recorded using LA with a laser-spot diameter of 5 mu m coupled to ICP-TOFMS. Quantification of elements ablated from each individual laser pulse was carried out by 100% mass normalization, and the 3D elemental concentration images generated match well with the expected distribution of elements. After laser-ablation imaging, the sample surface morphology was investigated using confocal microscopy, which showed substantial surface roughness and evidence of matrix-dependent ablation yields. Depth assignment based on ablation yields from heterogeneous materials, such as Opalinus clay rock, will remain a challenge for 3D LA-ICPMS imaging. Nevertheless, this study demonstrates quantitative 3D multielemental imaging of geological samples at a considerably higher image-acquisition speed than previously reported, while also offering high spatial resolution and simultaneous multielemental detection.