Nanoparticles of type Fe₃O₄-SiO₂-graphene oxide and coated with an amino acid-derived ionic liquid for extraction of Al(III), Cr(III), Cu(II), Pb(II) prior to their determination by ICP-OES

An amino acid derived ionic liquid, Fe₃O₄ nanoparticles and graphene oxide (GO) were used to prepare a material for the magnetic solid phase extraction (MSPE) of the ions Al(III), Cr(III), Cu(II) and Pb(II). The material was characterized by Fourier transform infrared spectral (FT-IR), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), magnetic analysis and isoelectric point (pI) analysis. It is shown to be a viable sorbent for the separation of these metal ions. Single factor experiments were carried out to optimize adsorption including pH values, ionic strength, temperature and solution volume. Following desorption with 0.1 M HCl, the ions were quantified by inductively coupled plasma optical emission spectrometry. Under the optimum conditions, the method provides a linear range from 10 to 170 μg· L⁻¹ for Al(III); from 4.0 to 200 μg· L⁻¹ for Cr(III); from 5.0 to 170 μg· L⁻¹ for Cu(II); and from 5.0 to 200 μg· L⁻¹ for Pb(II). The limits of detection (LOD) are 6.2 ng L⁻¹ for Al(III); 1.6 ng L⁻¹ for Cr(III); 0.52 ng L⁻¹ for Cu(II); and 30 ng L⁻¹ for Pb(II). Method performance was investigated by determination of these ions in (spiked) environmental water and gave recoveries in the range of 89.1%–117.8%. .