Magnetic SPME in micro-fluidics, speciation of Hg in cells

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Mercury is a well known toxicant with different exposure sources. Although its use on medical products is banned in many countries, other sources like environmental pollution or contaminated food still exist. Professor Bin Hu and co-workers have been recently researched how Hg species are distributed and even modified in cell cultures [1]. In their own words, this type of research is of paramount importance in order to fully understand the toxicity but also the cell protection mechanisms. The toxicological application is, in itself, interesting but the tools used in this research makes it attractive to "microextracters".

This study has come up several challenges related to cell culture studies. First of all, in this field the sample volume is usually limited so miniaturized instrumental techniques are required. In addition, the inherent nature of biosamples (complex matrices and low target concentrations) further complicate the situation. Our colleagues have on-line combined a micro-fluidic system (for sample preparation) and microHPLC-ICP-MS (for final analysis) to solve these limitations.

Magnetic nanoparticles
Let's focus our attention on the microfluidic system, where two different treatments are developed in a sequential way. At the beginning the cells are introduced into the system and lysed in a reactor channel, the final medium being transferred to an extraction reactor than contains magnetic nanoparticles (MNPs). These MNPs, which are immobilized by means of an external magnet, present mercapto propyl trimethoxy silane on the surface that retains Hg-compounds taking advantage of their strong interaction with thiol groups. The extraction step removes all the matrix components and preconcentrate the analytes for its final determination.

Absolute recoveries near to 100%, chip-to-chip reproducibility better than 8.5 %, potential reuse of the chip are remarkable characteristics. In addition, just 800 cells are enough to obtain the results, that have demonstrated the in-vitro demethylation of Me-Hg.

Reasons for reading the article
  • The research idea.
  • Complete and clarifying introduction.
  • Full description of the chip and how it works.
  • Deep discussion of the analytical results and the toxicological connotations


Reference

(1) Chip-based magnetic solid phase microextraction on-line coupled with microHPLC-ICP-MS for the determination of mercury species in cells. Link to the article

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