Gravimetric analysis of high purity tellurium for purity evaluation

Gravimetric analysis was utilized for purity evaluation of high purity tellurium, which was a raw material of a tellurium standard solution. Using a method in which tellurium was precipitated as elemental tellurium with hydrazinium after dissolution of the high purity tellurium, an avoidable positive error (ca. 0.02%) was observed. It seems that a cause of the positive error is oxidation of the tellurium or occlusion of the solvent during the precipitation. On the other hand, when the precipitated elemental tellurium was further converted into tellurium oxide by heating at 600 °C, the positive error disappeared. Finally, the purity of the starting tellurium was evaluated from the recovery of tellurium oxide with sufficient accuracy for a raw material of a tellurium standard solution (0.017% expanded uncertainty (k = 2)).