Spectrophotometric determination of trace amounts of cobalt with 2-hydroxybenzaldehyde-5-nitro-pyridylhydrazone in presence of surfactant after separation with Amberlite IRC-718 resin

2-Hydroxybenzaldehyde-5-nitro-pyridylhydrazone (2HB-5NPH) was synthesized and its application in the spectrophotometric determination of metal ions was studied in the presence of surfactants. A separation procedure, using a short column filled with Amberlite IRC 718, is proposed for the spectrophotometric determination of traces of cobalt. The influence of several ions, as interference, was discussed. The procedure was applied to determination of cobalt in mixture sample with satisfactory results (≥recovery 96%; relative error ≤2%; relative standard deviation ≤1.2% in the concentration range of 0.02–2.0 mg l⁻¹; detection limit, 0.01 mg l⁻¹ in solution). Control of the pH during the column operation is essential because the adsorption capacities are very sensitive to change in pH. Their separation was carried out in 0.005 M Malic acid, 1.5 M HCl, 2.0 M HNO₃ media.