Natural analcime zeolite modified with 2,3,5,6-tetra(2-pyridyl)pyrazine for preconcentration and determination of trace amounts of cadmium by flame atomic absorption spectrometry

Abstract

An analytical method using natural analcime zeolite modified with tppz (2,3,5,6-tetra-pyridylpyrazine) for preconcentration of cadmium, in a column system, and their sequential determination by flame atomic absorption spectrometry (FAAS), was developed. In this work, cadmium was adsorbed onto natural analcime zeolite modified with tppz and then was recovered by nitric acid. Solutions of cadmium were passed through a glass column packed with 100 mg of the sorbent material, at pH 5.0, and cadmium was eluted with 2.0 M HNO₃ at a flow rate of 2.0 ml min⁻¹. The relative standard deviation (RSD) for eight replicate determinations at the 2.5 μg of cadmium was ±0.94%. The calibration curve using the preconcentration system was linear from 0.01 to 4 μg ml⁻¹ in final solution with a correlation coefficient of 0.9993. This method was successfully applied for the determination of cadmium in various samples.