Solid-phase preconcentration of cadmium(II) using amino-functionalized magnetic-core silica-shell nanoparticles, and its determination by hydride generation atomic fluorescence spectrometry

We report on the synthesis and evaluation of aminated-CoFe2O4/SiO2 nanoparticles that can serve as a selective solid-phase sorbent for the extraction of cadmium ion. The nanoparticles consist of a magnetic CoFe2O4 core and an amino-modified silica shell. They can efficiently extract cadmium(II) ion and then can be isolated from the sample solution due to the magnetic nature of the core. The effects of the experimental conditions on the extraction process were optimized. Cadmium was then quantified by hydride generation atomic fluorescence spectrometry. The resulting calibration curve is linear in the concentration range of 0.01-10 mu g L-1, the instrumental detection limits (3 sigma) is 3.15 ng L-1 and the relative standard deviation is 4.9 % at the 1.0 mu g L-1 level (for n = 11). The enrichment factor is 50 (for 50 mL samples), and the adsorbent can be used for at least 45 cycles of preconcentration and elution. The method was applied to the determination of cadmium in environmental water samples, and successfully validated by analyzing two certified reference materials.