Adsorption behavior of cobalt(II) on chitosan and its determination by tungsten metal furnace atomic absorption spectrometry Original Research Article

Chitosan is derived from the deacetylation of chitin, which can adsorb metal ions and can dissolve in some organic acids. These properties are applied to the preconcentration of cobalt(II) in water samples and their determination by tungsten metal furnace atomic absorption spectrometry. Cobalt(II) is quantitatively adsorbed onto chitosan at a pH range 5.0–10.0 from sodium chloride solutions and their adsorption isotherms were fitted by the Freundlich equation. The chitosan with adsorbed cobalt(II) was separated from the sample solution by a membrane filter, and then dissolved in 2.0 cm3 of 0.5 mol dm−3 acetic acid solution. The aliquot of this resulting solution was introduced directly into a tungsten metal furnace and the absorbance of cobalt was measured by atomic absorption spectrometry. The detection limit for cobalt(II) was 0.005 μg/100 cm3 by the proposed procedure (S/N≥3). The relative standard deviations (n=5) were 3.8% for 0.10 μg Co(II)/100 cm3, and 4.3% for 0.05 μg Co(II)/100 cm3. This method was applied to the determination of trace amounts of cobalt(II) in the environmental water samples.