Flame atomic absorption determination of cobalt in water after extraction of its morpholinedithiocarbamate complex

A preconcentration system for the determination of cobalt in water was developed. The studied system uses a glass column packed with Amberlyst A-26 resin modified with ammonium morpholinedithiocarbamate. The metal was quantitatively retained in the column containing 1.30 g of resin modified with 6% (m/m) of chelating reagent, at pH 5.5, resulting in a coloured complex which was eluted with 10.0 mL of ethanol. The final solution was analysed by flame atomic absorption spectrometry at 240.7 rim. Using these conditions a preconcentration factor of 25 was obtained and depending on the concentration of cobalt present in the solution it was possible to re-utilise the packed column several times. The limit of quantification was 2.0 [mu g L-1 with RSD of 2.9%. The foreign ions effect was studied and only Cd(II) and Ni(11) showed interference. The proposed method showed to be simple, of low cost, easy to handle and has been applied for the determination of cobalt in natural water samples.