Synthesis and Application of Glutaric Dihydrazide Modified Multiwalled Carbon Nanotubes for Selective Solid-Phase Extraction and Preconcentration of Cu(II), Zn(II), Ni(II), and Fe(III)

An SPE method for selective separation-preconcentration of Cu(II), Zn(II), Ni(II), and Fe(III) on multiwalled carbon nanotubes (MWCNTs) modified by glutaric dihydrazide prior to flame atomic absorption spectrometric determination was investigated. The adsorption was achieved quantitatively on MWCNTs at pH 5.0, and then the retained metal ions on the adsorbent were eluted with 1 M HNO3. The effects of analytical parameters including pH of the solution, eluent type, sample volume, and matrix ions were investigated for optimization of the presented procedure. The adsorption capacity of the adsorbent at optimum conditions was found to be 33.6, 29.2, 22.1, and 36.0 mg/g for Cu(II), Zn(II), Ni(II), and Fe(III), respectively. The LOD values of the method were 0.21, 0.11, 0.24, and 0.27 mu g/L for Cu(II), Zn(II), Ni(II), and Fe(III), respectively. The RSDs were lower than 3.01%. The method was applied for the determination of analytes in soil, river water, and wastewater samples with satisfactory results.