▎ 摘　　要

Graphene oxide nanosheets were modified with magnetite nanoparticles, and a dithiocarbamate-terminated hyper branched polyamidoamine dendrimer was then covalently attached to their surface. The resulting material is shown to be an efficient sorbent for preconcentration of the Pb(II), Cd(II), Ni(II), Cu(II) and Cr(III) via ultrasound-assisted magnetic solid phase extraction. The sorbent was characterized by transmission electron microscopy, field emission scanning electron microscopy, FT-IR, X-ray diffraction and vibrating sample magnetometry. The effects of pH value, sorbent dosage, eluent volume, and sonication time were optimized by central composite design. The metals were quantified by flame atomic absorption spectroscopy (FAAS). Under optimized conditions, the method has a linear response in 3.5-150, 0.9-15, 3-100, 1.8-50 and 2.6-75 mu g L-1 concentration range for Pb(II), Cd(II), Ni(II), Cu(II) and Cr(III), respectively. The detection limits are as low as 1.0, 0.27, 0.9, 0.54 and 0.8 mu g L-1 for Pb(II), Cd(II), Ni(II), Cu(II) and Cr(III), respectively. [GRAPHICS]