Detection of mercury in single mammalian cells at attogram level by SC-ICP-MS

Mercury (Hg), a global pollutant, poses health risks to humans and mammals even at low exposure levels. However, current analytical methods face challenges in quantifying cellular Hg at ultralow concentrations. In this study, we developed a sensitive single-cell inductively coupled plasma-mass spectrometry (SC-ICP-MS) method by utilize a temperature-controlled introduction system to trace Hg in individual mammalian cells.

Sensitivity was significantly enhanced through a personalized tuning process, which increased the instrument sensitivity of Hg ions (Hg²⁺) by 28.8 %. Through optimization of detection conditions, we achieved an improved transport efficiency (TE) of 27.3 % for single-cell detection in THP-1 cells. By implementing the comprehensively optimized method, we attained an exceptionally low single-cell-level Hg mass detection limit (LOD_m) of 0.01 fg per cell, coupled with a cell density detection limit (LOD_d) of 8.1 × 10² cells mL^-1, resulting in a Hg concentration detection limit (LOD_c) of 0.008 ng L^-1. This validated method demonstrated robust applicability across multiple mammalian cell types, revealing that Hg content (m) at the single-cell level exhibited exponential growth with increasing exposure concentration, while the heterogeneity of Hg displayed an initial rise before reaching a plateau or decreasing.

This study establishes a highly sensitive and reproducible method for monitoring single-cell Hg content and heterogeneity at environmentally low exposure levels. The technical advances provide a robust methodological foundation for assessing element-specific toxicity across different mammalian cell types, supporting the health risk evaluation in low-dose scenarios.