Thiol-grafted magnetic polymer for preconcentration of Cd, Hg, Pb from environmental water followed by inductively coupled plasma mass spectrometry detection

Highlights: • Thiol modified magnetic polymer (MPPs-SH) was prepared by click reaction. • MPPs-SH exhibited high S content (5.4%) and good selectivity for Cd, Hg and Pb. • A method of MSPE-ICPMS was developed for trace Cd, Hg and Pb analysis. • It is simple and sensitive with a fast adsorption/desorption kinetics. A novel thiol-grafted magnetic polymer (MPPs-SH) was synthesized by "click reaction" between 1,2-ethanedithiol and Fe₃O₄@SiO₂@poly (ethylene glycol dimethacrylate -co- glycidyl methacrylate). The resultant MPPs-SH had high S content (5.4 wt%) and exhibited large specific surface area (156.8 m² g⁻¹) as well as high adsorption capacity of 254, 64.2, 56.6 mg g⁻¹ for mercury, cadmium and lead ions, respectively. With the prepared MPPs-SH as sorbent, a method of magnetic solid phase extraction combined with inductively coupled plasma mass spectrometry was developed for the quantification of trace mercury, cadmium and lead in environmental water samples. The extraction conditions including sample pH, sample volume, sorbent amount, adsorption/desorption time and elution volume were optimized. Under the optimal conditions, three heavy metal ions were extracted from 150 mL aqueous solution in 10 min and eluted by 0.2 mol L⁻¹ HNO₃ containing 2% thiourea in 5 min. The method presented low limits of detection (0.21, 0.82 and 2.9 ng L⁻¹) for target ions. The accuracy of the method was validated by using Certified Reference Materials of Environmental Water including GSB 07–1185–2000 (201435), GSB 07–1183–2000 (201239) and GSB 07–3173–2014 (202046). The application potential was further validated by the determination of trace mercury, cadmium and lead in Yangtze river and East lake water samples. The content of target heavy metal ions in tested water sample was found to be in the range of 6.40–195 ng L⁻¹, and the recoveries of 86.4–109% were obtained at three spiking concentration levels for mercury, cadmium and lead ions.