Preconcentration and determination of lead and cadmium in water samples with a MnO2 coated carbon nanotubes by using ETAAS

A procedure for separation and preconcentration trace amount of Pb(II) and Cd (II) by nano-sized manganese dioxide functionalized multi-wall carbon nanotubes (MnO2/MWCNTs) packed column has been proposed. Various influencing parameters on the separation and preconcentration of trace metals, such as pH, flow rate, concentration of eluent, sample volume and interference ions, were studied. Under the optimized conditions (pH 6, flow rate 2.5 mL min− 1), Pb(II) and Cd (II) were retained on the column, then quantitatively eluted by 1.5 mL 1.5 mol L− 1 nitric acid solution and determined by electrothermal atomic absorption spectroscopy (ETAAS). The detection Limits of Pb(II) and Cd(II) for an extraction of 5.0 mL water sample were 4.4 and 1.5 ng L− 1, respectively. The relative standard deviations (R.S.D.) were 3.2% and 2.5% for Pb(II) and Cd(II), respectively. The optimized method was successfully applied to the determination of Pb(II) and Cd(II) in certified reference materials and real water samples.

► Preconcentration of Pb and Cd was carried out using MnO2/CNTs composite in water samples.
► The enrichment factor of the method is 100.
► The maximal adsorption capacities for Pb(II) and Cd(II) are 6.7 and 9.1 mg g− 1, respectively.