Allylthiourea functionalized magnetic adsorbent for the extraction of cadmium, copper and lead ions prior to their determination by atomic absorption spectrometry

A quick and sensitive method was developed for the trace determination of Cd(II), Pb(II) and Cu(II) ions in water and bean samples. It is based on a combination of magnetic solid phase extraction (MSPE) and graphite furnace atomic absorption spectrometry (GFAAS). Allylthiourea (which contains abundant sulfur and nitrogen atoms) was copolymerized with ethylene dimethacrylate on the surface of magnetite (Fe₃O₄) nanoparticles to prepare a new adsorbent for use in MSPE. Various technologies were used to characterize the morphology, spectroscopic and magnetic properties of the adsorbent, and several parameters that affect the extraction performance were optimized. The adsorbent can enrich Cd(II), Pb(II) and Cu(II) ions via chelation interaction. Following elution with 0.1 mol·L⁻¹ HNO₃, the ions were quantified by GFAAS. Under the most favorable conditions, the limits of detection are from 3.3–7.2 ng·L⁻¹ for water samples, and 1.1–1.5 μg·kg⁻¹ for beans. The method displays wide linear analytical ranges and good precision. It was successfully applied to the determination of the metal ions in water and bean samples. The recoveries from spiked samples ranged between 80.5 and 114% in water, and from 82.2 to 118% in bean samples. The relative standard deviations of reproducibility were < 10%.

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