Determination of trace amounts of zinc by flame atomic absorption spectrometry after separation and preconcentration onto modified natural analcime zeolite loaded 2,3,5,6-tetra(2-pyridyl)pyrazine

Zinc ions were separated by solid phase extraction onto modified natural analcime zeolite loaded with 2,3,5,6-tetra(2-pyridyl)pyrazine (TPPZ). Extraction efficiency and the influence of sample matrix, flow rate, pH, and type and minimum amount of stripping eluent were investigated. Solutions of zinc ions were passed through a glass column packed with 1.0 g of the sorbent at pH range of 3.8-4.4. The adsorbed zinc ions were eluted with 5.0 mL of 2.0 MHNO3 at a flow rate of 1.0 mL min-1. The calibration curve using the preconcentration system was linear from 0.05 to 2.0 μg mL-1 in final solution with a correlation coefficient of 0.9991. The relative standard deviation (RSD) for eight replicate determinations at 0.5 μg mL-1 zinc was ± 0.92%. Detection limit was 2.9 ng mL-1 in final solution and preconcentration factor was 170. The proposed method was successfully applied to the determination of zinc in various standard and water samples. KEY WORDS: Zinc determination, Solid-phase extraction, Analcime zeolite, Preconcentration, 2,3,5,6-Tetra(2-pyridyl)pyrazine Bull. Chem. Soc. Ethiop. 2010, 24(1), 127-132.