Co-Hydride Enhancement Effects in Cadmium,Zinc and Thallium Hydride Generation Measurements

Until recently hydride generation (HG) technique had been applied to only a limited number of elements. In attempts to extend the technique to cadmium, Guo and Guo found that the presence of thiourea together with cobalt enhanced the signal intensity of the Cd volatile species. This finding was repeated and confirmed by many authors. Moreover, Ga and Si, Fe and Ni were used to improve the sensitivity for Cd determination. Recently, the vapour generation of Zn species was performed using an intermittent flow reactor by Guo and Guo,it was found that Ni and Co ions greatly enhanced the signal intensity of zinc. Early in 1984,Yan and co-works reported that the addition of hydride-forming elements, especially tellurium, "accelerated" the formation of thallium hydride rapidly, and suggested a complex hydride was formed. According to these reports, it seems that the addition of certain foreign ions has a positive effect to such elements as Cd, Zn, and Tl, which form unstable hydrides. But the mechanism of the effect of these foreign ions remains unexplained.