Determination of Cu²⁺, Zn²⁺ and Pb²⁺ in biological and food samples by FAAS after preconcentration with hydroxyapatite nanorods originated from eggshell

Hydroxyapatite nanorods (HAPNRs) were prepared from recycled eggshell by using precipitation method. The structure of the HAPNRs was physicochemically and morphologically characterized by X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy. The resulting HAPNRs were used for solid phase extractive preconcentration of Cu²⁺, Zn²⁺ and Pb²⁺ prior to its determination by flame atomic absorption spectrometry. Experimental variables that influence the quantitative extraction of metal ions were optimized by both batch and column methods. The analytes were quantitatively sorbed on the matrix between pHs 6 and 9. The maximum sorption capacity of the HAPNRs has been found to be 2.43, 2.37 and 2.53 mmol g⁻¹ for Cu²⁺, Zn²⁺ and Pb²⁺, respectively, with the preconcentration factor of 250. The 3σ detection limit and 10σ quantification limit for Cu²⁺, Zn²⁺ and Pb²⁺ were found to be 0.72, 0.55 and 5.12 μg L⁻¹ and 2.40, 1.83 and 17.06 μg L⁻¹, respectively. The calibration curves were linear up to 250 μg L⁻¹ for Cu²⁺, 300 μg L⁻¹ for Zn²⁺ and 400 μg L⁻¹ for Pb²⁺. Accuracy of the proposed method was verified using certified reference materials (NCS ZC85006 Tomato, Seronorm Trace Elements Whole Blood L-1, Seronorm Trace Elements Whole Blood L-3 and Seronorm Trace Elements Urine). The present method was successfully applied to the analysis of these metal ions in sea water, biological and food samples. - Highlights: • Hydroxyapatite nanorods were prepared from egg shell. • The prepared nanoparticles showed fast adsorption with high adsorption capacities of the metal ions. • The nanostructures were used for solid phase extraction of copper, zinc and lead ions prior to determination by FAAS. • Accuracy of the method was validated by analyses of certified reference materials