Magnetic solid phase extraction coupled with inductively coupled plasma mass spectrometry for the speciation of mercury in environmental water and human hair samples

Abstract

In this work, γ-mercaptopropyltrimethoxysilane (γ-MPTS) modified Fe3O4@SiO2 magnetic nanoparticles (MNPs) was successfully prepared, and characterized by Fourier transform infrared spectrometer (FT-IR), Transmission electron microscope (TEM) and Vibrating sample magnetometer (VSM). The sorption performance of the prepared Fe3O4@SiO2@γ-MPTS MNPs towards methylmercury (CH3Hg+) and inorganic mercury (Hg2+) was investigated. It was found that CH3Hg+ and Hg2+ could be simultaneously retained on the prepared Fe3O4@SiO2@γ-MPTS MNPs, and the quantitative elution of CH3Hg+ and total mercury (THg) was achieved by using 1.5molL−1 HCl containing 0.01% and 3% thiourea (m/v), respectively. And the levels of Hg2+ were obtained by subtracting CH3Hg+ from THg. Based on the above facts, a method of magnetic solid phase extraction (MSPE) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for the speciation of CH3Hg+ and Hg2+. Various experimental parameters affecting MSPE of CH3Hg+ and Hg2+ such as pH, eluent, sample volume, and co-existing ions have been studied. Under the optimized conditions, the limits of detection (LODs) for CH3Hg+ and THg were 1.6 and 1.9ngL−1, respectively. The accuracy of the proposed method was validated by analysis of a Certified Reference Material NRCC DORM-2 dogfish muscle, and the determined values are in good agreement with the certified values. The proposed method has also been successfully applied for the speciation of CH3Hg+ and Hg2+ in environmental water and human hair samples.