Speciation of mercury using high-performance liquid chromatography-inductively coupled plasma mass spectrometry following enrichment by dithizone functionalized magnetite-reduced graphene oxide

A facile method of magnetic solid-phase extraction high-performance liquid chromatography-inductively coupled plasma mass spectrometry (MSPE-HPLC-ICP-MS) based on a magnetic adsorbent that was prepared by simply and directly adsorbing dithizone on the surface of the magnetite-reduced graphene oxide composites was developed to preconcentrate trace mercury species in environmental samples. Parameters influencing the synthesis of the adsorbents and extraction, including the ratio of GO to iron (III) acetylacetonate, solution pH, adsorption time, desorption time and the component of the eluent, were optimized. Under the optimized conditions, the enrichment factors were 400 and 380 (400 mL water sample) for inorganic mercury (IHg) and methylmercury (MMHg), respectively. The detection limits (38) of the proposed method were 0.48 and 0.17 ng L-1 for IHg and MMHg. The spiked recoveries (91.5-111%) and standard deviation ( < 3.1%) in real water samples indicated that the method had high reproducibility and accuracy. This proposed MSPE-HPLC-ICPMS method, with simple operation, high enrichment factors and high sensitivity, was successfully applied for the determination of mercury species at trace levels in environmental water samples, including river water, ground water, sea water and sewage effluent, and fish samples.