A novel sampling strategy for cobalt determination by ETAAS using polyurethane foam

A new strategy for the determination of cobalt in aqueous and biological materials is presented. The methodology is based on solid sampling of polyurethane foam (PUF) previously loaded with cobalt-thiocyanate complex. Cobalt was extracted from aqueous solution (sample) by PUF in a medium containing 0.5 mol l(-1) sodium thiocyanate and 0.1 mol l(-1) hydrochloric acid. With this procedure it was possible to extract cobalt from saline matrices. By cleaning the vapor phase inside the graphite furnace, background interferences were minimized. The obtained results showed that PUF can be easily eliminated from the graphite tube by a pyrolysis step at 550 degreesC and cobalt can be determined without using any matrix modifier. The method was validated by analysis of certified reference materials (biological samples) and by using recovery tests employing saline samples. External calibration using aqueous standards was possible for cobalt determination.