Influence of some matrix elements on atomization of cobalt in graphite-furnace atomic-absorption spectrometry

The influence of some chlorine, sulphur and phosphorus compounds on cobalt atomization in a graphite cuvette has been investigated. On the basis of atomization curves and estimated atomization energies the mechanisms of several processes have been proposed. Excess of chlorine is responsible for losses of cobalt as chloride and also for formation of a compound with graphite which causes atomization to occur at a temperature 300 K higher than that in the absence of graphite. In presence of sulphur, the atomization goes through sulphide formation but a reaction with graphite is also suspected. The presence of phosphorus significantly increases the rate of atomization, which enhances the peak height for cobalt. The mechanism probably involves dissociation of phosphate salts.