Solid-phase extraction using multiwalled carbon nanotubes and quinalizarin for preconcentration and determination of trace amounts of some heavy metals in food, water and environmental samples

A solid phase extraction procedure has been developed using multiwalled carbon nanotubes (MWCNTs) as a solid sorbent and quinalizarin [1,2,5,8-tetrahydroxyanthracene-9,10-dione] as a chelating agent for separation and preconcentration of trace amounts of some heavy metal ions, Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II) before their determination by flame atomic absorption spectroscopy (FAAS). The influences of the analytical parameters, including pH, amounts of quinalizarin and adsorbent, sample volume, elution conditions such as volume and concentration of eluent, flow rates of solution and matrix ions, were investigated for the optimum recoveries of the analyte ions. No interference effects were observed from the foreign metal ions. The preconcentration factor was 100. The detection limit (LOD) for the investigated metals at the optimal conditions were observed in the range of 0.30-0.65 mu g L-1. The relative standard deviation (RSDs), and the recoveries of standard addition for this method were lower than 5.0% and 96-102%, respectively. The new procedure was successfully applied to the determination of analytes in food, water and environmental samples with satisfactory results.