Analytical Sciences

Determination of Cobalt and Nickel by Graphite-Furnace Atomic Absorption Spectrometry after Coprecipitation with Scandium Hydroxide

Tomoharu MINAMI, Kousuke ATSUMI, and Joichi UEDA

Faculty of Education, Kanazawa University, Kakumamachi, Kanazawa 920-1192, Japan

Trace amounts of cobalt and nickel in a water sample were quantitatively coprecipitated with scandium hydroxide at pH 8.0 - 10.5. Because the coprecipitant could be easily dissolved with 1 mol dm^-3 nitric acid, and the presence of up to 10 mg cm^-3 of scandium did not interfere with the graphite-furnace atomic absorption spectrometric determination of cobalt and nickel, the volume of the final solution prepared for the determination could be minimized down to 0.5 cm^-3. The concentration factor was 400-fold and the detection limits (signal to noise = 2) were 5.0 pg cm^-3 of cobalt and 10.0 pg cm^-3 of nickel in 200 cm³ of the initial sample solution. The 27 diverse ions investigated did not interfere with the determination in at least a 500-fold mass ratio to cobalt or nickel. The proposed method was successfully applied to the determination of trace amounts of cobalt and nickel in river-water samples.

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