Flame Atomic Absorption Spectrometric Determination of Trace Amounts of Zinc and Thallium in Different Matrixes after Solid Phase Extraction on Modified Multiwalled Carbon Nanotubes

The potential of modified multiwallcd carbon nanotubes, as a solid-phase extraction sorbent for the simultaneous separation and preconcentration of zinc and thallium has been investigated. Zinc and thallium were adsorbed quantitatively onto modified multiwalled carbon nanotubes in the pH range of 3 6.5. Parameters influencing the simultaneous preconcentration of Zn(II) and Tl(I) ions such as pH of the sample, sample and eluent flow rate, type and volume of elution solution and interfering ions, have been examined and optimized. Linearity was maintained between 0.1 to 20.0 μg·mL for thallium and 20.0 ng·mL to 5.0 μg·mL for zinc in the final solution. The defection limits based on three times the standard deviation of the blank signal (n = 8) for thallium and zinc were 5.1 and 1.4 ng·mL, respectively. Seven replicate determination of a mixture of 5.0 and 0.2 μg·mL of thallium and zinc in the final solution gave a mean absorbance of 0.085 and 0.074 with relative standard deviation 1.5% and 1.7%, respectively. The method has been applied for the determination of trace amounts of zinc and thallium in biological and water sample with satisfactory results.