Exploring the applicability of nano-selenium for capture of mercury vapor: Paper based sorbent and a chemical modifier in graphite furnace atomic absorption spectrometry

The ability of the selenium nanoparticles (SeNPs) to capture mercury (Hg) is a subject of interest as this concept can be applied to reduce mercury poisoning cases to certain extent. In this work, SeNPs were fabricated on a paper and used as sorbent for capturing mercury vapor. The formation of the stable HgSe on the paper sorbent after the sequestration was visible to the naked eye for mercury concentration of higher than 200 μg L-1, corresponding with the discoloration of the paper sorbent from dark orange to gray color. The gray color was more intense with increasing Hg concentrations from 200 to 300, 500, and 1000 μg L-1. Therefore, color analysis software was used as a semi-quantitative technique for mercury analysis. The mercury captured was also analyzed with the inductively coupled plasma mass spectrometry (ICP-MS). After confirming that SeNPs helps capture mercury, it was further applied as a chemical modifier in graphite furnace atomic absorption spectrometry (GFAAS) for mercury determination. The SeNPs (410 mg L-1) allowed the use of pyrolysis temperature up to 300 °C with adequate sensitivity. Calibration curve was constructed from 100 to 500 μg L-1 with good linearity (R2 = 0.9968). With the use of SeNPs, 15 times sensitivity improvement was obtained compared to that without the use of any chemical modifier. The detection limit (N = 10 at 3σ) was calculated at 2 μg L-1 for the Hg standard. The proposed modifier was used for analyzing mercury in the saliva sample. Apart from minimizing extensive sample pretreatment process, the recovery percentage of Hg from the spiked sample was found to be approximately 90% (RSD 0-2%) with the help of the SeNPs modifier. This work exhibits multi-dimensional applications of SeNPs towards mercury analysis.