Quantitative Analysis of Elements in Coal Using In Situ Characterization Techniques

Coal hosts trace elements of environmental and economic significance in a complex organo-mineral matrix. The absence of matrix-matched certified reference materials for organic constituents limits conventional in situ elemental quantification. This study develops a multiscale characterization framework integrating laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), a TESCAN Integrated Mineral Analyzer (TIMA), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). TIMA provides centimeter-scale datasets on mineral abundance, particle size, and paragenetic relationships. ToF-SIMS resolves spatial associations between organic macerals and metallic elements at submicron scales. LA-ICP-MS combines single-mineral quantitative analysis with elemental mapping to characterize elemental distributions within coal. A mineral-referenced approach is further explored for estimating trace element concentrations in organic matter from LA-ICP-MS mapping signals, while recognizing uncertainties associated with matrix effects. The integrated framework characterizes the distribution of critical metals, including Li, Ga, and Ge, and their partitioning across mineral–organic interfaces, linking bulk geochemical information with microscale distributions. These results provide a geochemical basis for targeted recovery of strategic metals and prediction of hazardous element migration during coal utilization. The framework also offers a methodological approach for investigating elemental occurrence and migration in other organic-rich geological systems, including shale and mudstone.