▎ 摘　　要

In the present study, for the first time, the magnetic graphene oxide was simultaneously functionalized and reduced with the aim of imidazole-based L-histidine amino acid (rGO/Fe3O4-histidine). The prepared nanocomposite was characterized by field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, and vibrating sample magnetometer. The synthesized rGO/Fe3O4-histidine nanosheets were implied for solid phase extraction of ultra-trace amounts of Zn2+, Cu-,(2+) and Mn2+ from biological samples prior to ICP-OES determination. The calibration curves were linear in the concentration ranges of 0.4-182.0, 0.4-215.0, and 0.2-168.5 mu g L-1 for Zn2+, Cu2+, and Mn2+, respectively. The limits of detection were 0.12, 0.10, and 0.04 mu g L-1 for Zn2+, Cu2+, and Mn2+, respectively. The relative standard deviations (RSDs) at 50.0 mu g L-1 for single-sorbent repeatability and sorbent-to-sorbent reproducibility were less than 6.7 and 9.2% (n = 5), respectively. The accuracy of the method was confirmed by the analysis of a serum quality control material (QCM, Seronorm (TM) Human Serum REF NO 203105) and hair certified reference material (CRM, Human Hair IAEA-086).