magnetic dispersive solid phase extraction of silver ions

Abstract: common sorbents applied in spe suffer from some disadvantages including low selectivity toward the analyte, low stability as well as low sorption capacity. to solve these problems, nanostructured materials are promising due to their high surface area, enhanced active sites, and abundant functional groups on their surfaces. among these materials, carbon nanotubes are interesting sorbents owing to their unique properties of extremely high surface-to-volume ratio, as well as good electrical and thermal conductivities [1]. however, they have some limitations such as hydrophilicity, small size, and high dispersibility. moreover, they have low selectivity toward metal ions. the problem of separation can be overcome by the combination of carbon nanotubes with magnetic nanoparticles [2] and the selectivity toward metal ions can be achieved through the modification of carbon nanotubes surface with suitable chelating agents. in this study, the magnetic multi-walled carbon nanotube (mwcnt) coated with diphenylthiocarbazone was synthesized and characterized by ft-ir, xrd, fesem, and vsm. the prepared sorbent was applied for dispersive magnetic solid-phase extraction of trace silver ions from aqueous solutions before flame atomic absorption spectrometric determination. important factors affecting the extraction of the analyte were investigated and optimized. under the optimized conditions, the limit of detection based on 3sb/m was 0.15 μg l-1 and the maximum sorption capacity of the sorbent was 42.7 mg g-1 of silver ions. the relative standard deviation at 10 μg l-1 of silver (n = 5) was 2.8%. the method was successfully applied to the determination of silver ions in different water samples.