Quantitative analysis of selenium and mercury in biological samples using LA-ICP-MS†

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has emerged as a powerful analytical tool to spatially resolve elemental quantification and multi-element bioimaging. This study presents a comprehensive methodology of LA-ICP-MS for the simultaneous quantification of selenium (Se) and mercury (Hg) in biological matrices, achieving micrometer-scale spatial resolution and maintaining analytical robustness. Critical challenges in Se quantification arising from potential spectral interferences were resolved through collision/reaction cell (CRC) technology optimization and strategic isotope selection (⁷⁷Se and ⁸²Se), enabling interference-free detection. Notably, this study pioneered the quantitative characterization of polyatomic interferences through interference modeling. Distinct matrix-dependent signal behaviors were observed between organic-rich tissues (e.g., liver) and protein-dominated matrices (e.g., gelatin), underscoring the necessity for matrix-specific calibration strategies. The method demonstrated that both LA-ICP-MS and LA-ICP-MS/MS exhibited high precision (<10% relative bias) in quantifying Se and Hg. Subsequent application to controlled exposure models provided more detailed information on Se/Hg biodistribution patterns. Collectively, this analytical advancement provides a valid method for investigating detoxification dynamics and elemental redistribution mechanisms in organs, particularly when the analysis was integrated with high-resolution mapping of Se–Hg antagonism at sub-organ resolution.