Atomic absorption determination of cobalt after preconcentration by 1-(2-pyridylazo)-2-naphthol immobilized on surfactant-coated alumina

1-(2-Pyridylazo)-2-naphthol loaded onto sodium dodecyl sulfate-coated alumina has been used as a new chelating sorbent for the preconcentration of trace metals prior to atomic absorption spectrometric determination. The effect of PH, flow rate of sample solution, and foreign ions on the sorption of cobalt(II) by this sorbent has been investigated. Preconcentration of cobalt and its separation from various concentrations of manganese are successful from aqueous solutions in the PH range 4-5. The elution of cobalt with acetone from the sorbent column is quantitative. The relative standard deviations at the 20 and 100 mu g ml(-1) levels were 4.0 and 1.4%, respectively. As there are no observable effects due to changes in the volume of sample solution up to a volume of I liter, a preconcentration factor of 100 can be achieved. The method has been applied to the determination of cobalt in mineral water and polluted river water. (C) 1999 Academic Press.