▎ 摘　　要

Herein, a novel imidazolium-functionalized magnetic graphene oxide (GO@ magnetite@Im) composite was synthesized and utilized for speciation analysis of Cr(III) and Cr(VI) via determination by electrothermal atomic absorption spectrometry. The nanosorbent was characterized with various techniques. This material is illustrated to represent a viable sorbent for separation and removal of Cr(III) and Cr(VI) ions. GO@magnetite@Im sorbent exhibited selectivity toward Cr(VI) species at pH = 2.0 through electrostatic interaction with imidazolium rings, while Cr(III) and Cr(V) species were sorbed on the active sites of the sorbent at pH = 6.0, simultaneously. No preoxidation or prereduction step was performed. Experimental design methodology was employed to find the best extraction conditions by exploring the affecting parameters on extraction procedure. Under the best optimized extraction conditions the linearity was 4-350 ng L-1 for Cr(VI) and 5-400 ng L-1 for total chromium. Detection limit and relative standard deviation for Cr(VI) were 1.2 ng L-1, and 6.8%, respectively, while these values for total chromium were 1.9 ng L-1 and 8.0%, respectively. The accuracy of the developed method was confirmed by analyzing two certified reference materials. Ultimately, this method was utilized for rapid extraction and speciation analysis of Cr(III) and Cr(VI) in water samples and food samples.