Chip-Based Magnetic Solid-Phase Microextraction Online Coupled with MicroHPLC-ICPMS for the Determination of Mercury...

Trace mercury speciation in cells is critical to understand its cytotoxicity and cell protection mechanism. In this work, we fabricated a chip-based magnetic solid-phase microextraction (MSPME) system, integrating a cell lysis unit as well as a sample extraction unit, and online combined it with micro high-performance liquid chromatography (microHPLC)-inductively coupled plasma mass spectrometry (ICPMS) for the speciation of mercury in HepG2 cells. Magnetic nanoparticles with sulfhydryl functional group were synthesized and self-assembled in the microchannels for the preconcentration of mercury species in cells under an external magnetic field. The enrichment factors are ca. 10-fold, and the recoveries for the spiked samples are in the range of 98.3-106.5%. The developed method was used to analyze target mercury species in Hg(2+) or MeHg(+) incubated HepG2 cells. The results demonstrated that MeHg(+) entered into the HepG2 cells more easily than Hg(2+), and part of the MeHg(+) might demethylate into Hg(2+) in HepG2 cells. Besides, comprehensive speciation of mercury in incubated cells revealed different detoxification mechanisms of Hg(2+) and MeHg(+) in Hg(2+) or MeHg(+) incubated HepG2 cells.