Speciation of organic/inorganic mercury and total mercury in blood samples using vortex assisted dispersive liquid-liquid microextraction based on the freezing of deep eutectic solvent followed by GFAAS.

In this research, a new vortex assisted dispersive liquid-liquid microextraction based on the freezing of deep eutectic solvent (VADLLME-FDES) has been developed for the determination of organic mercury (R-Hg) and inorganic mercury (Hg2+) in blood samples prior to their analysis by graphite furnace atomic absorption spectrometry (GFAAS). In this method, a green solvent consisting of 1-octyl-3-methylimidazolium chloride and 1-undecanol was used as an extraction solvent, yielding the advantages of material stability, low density, and a suitable freezing point near room temperature. Under the optimum conditions, enrichment factor is 112. The calibration graph is linear in the range of 0.30-60 µg L-1 and limit of detection (LOD) is 0.10 µg L-1. Repeatability and reproducibility of the method based on seven replicate measurements of 5.0 µg L-1 of Hg2+ in analyzed samples were 3.7% and 6.2%, respectively. The relative recoveries of blood samples which have been spiked with different levels of Hg2+ are 90-109%. A new deep eutectic solvent consists of two parts: [DMIM]Cl and 1-undecanol in the molar ratio of 1-2. The accuracy of the proposed procedure was also assessed by determining the concentration of the mercury in a standard reference material. All organic mercury (R-Hg) species were converted to Hg2+ and finally, the concentration of R-Hg is simply calculated by mathematically subtracting the concentrations of Hg2+ from the concentration of total mercury (t-Hg). The extraction methodology is simple, rapid, cheap and green since small amounts of non-toxic solvents are necessary.