Ultratrace determination of cadmium(ii) ions in water samples using graphite furnace atomic absorption spectrometry after separation and preconcentration using magnetic activated carbon nanocomposites

Abstract

The main purpose of the present study is sorption/preconcentration of trace amounts of cadmium using a magnetic activated carbon nanocomposite (MAC) as an adsorbent in various water samples using graphite furnace atomic absorption spectrometry (GFAAS). The advantages of this method include the elimination of organic solvent and easy separation of magnetic nanocomposites from the bulk solution by applying a magnet without any preliminary centrifugation and filtration steps. Initially, MAC was prepared by a sonochemical approach and characterized by FT-IR and TEM. Cadmium ions from 100 mL sample solution were then adsorbed on the prepared sorbent by batch mode at pH 7. After sedimentation of MAC, quantitative desorption occurs using 0.5 mL of 0.5 mol L⁻¹ HCl. The effects of various parameters on the solid-phase extraction procedure efficiency including pH, sample volume, equilibrium time, type and concentration of eluent have been thoroughly investigated and optimized. Under the optimal experimental conditions, the detection limit (LOD) based on three times the standard deviation of the blank signals (n = 8) was 4 ng L⁻¹. The relative standard deviation (RSD) resulting from the analysis of five replicate solutions containing 100 ng L⁻¹ Cd(II) was 3.5%. The effect of potentially interfering ions on the percent recovery of cadmium ions was also studied. The accuracy of the method was verified using the analysis of a certified reference material. The proposed method was successfully applied to determine Cd(II) ions in aqueous real solutions.