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Solid phase extraction and flame atomic absorption spectrometric determination of trace amounts of cadmium and lead in water and biological samples using modified TiO2 nanoparticles

A solid phase extraction procedure for the separation and preconcentration of trace amounts of Cd(II) and Pb(II) using the alizarin red S modified TiO2 nanoparticles prior to their determination by flame atomic absorption spectrometry has been proposed. The influences of some analytical parameters such as pH, flow rates of sample and eluent, type and concentration of the eluent, and interfering ions on the recovery of Cd(II) and Pb(II) by the sorbent were investigated. The analytes were quantitatively sorbed from the aqueous solution at pH 5.5 onto a microcolumn packed with the sorbent and recovered with 2.0 mL of 1.5 mol L−1 hydrochloric acid. Under the optimum experimental conditions, the detection limits for Cd(II) and Pb(II) were 0.11 and 0.30 ng mL−1 and the relative standard deviations for ten replicate measurements of 5.0 and 50.0 ng mL−1 of Cd(II) and Pb(II) were 2.1 and 1.9%, respectively. A sample volume of 200 mL resulted in a preconcentration factor of 100. The method was successfully applied to the determination of Cd(II) and Pb(II) in water and biological samples, and accuracy was examined by the recovery experiments, independent analysis using electrothermal atomic absorption spectrometry, and analysis of a water standard reference material (SRM 1643e).