RADIOMETRIC DETERMINATION OF TELLURIUM WITH IODIDE AND CO-60 LABELED TRIS(1,10-PHENANTHROLINE)COBALT(II)

A simple and sensitive radiometric method for the determination of tra ce amounts of tellurium is described. The method involves an indirect radiometric procedure in which an ion-pair complex, formed between TeI 62- and cobalt-60 labelled tris(1,10-phenanthroline)cobalt(II) ion, is extracted into 1,2-dichloroethane from potassium iodide and sulphuric acid media. The activity of the cobalt-60, which is proportional to t he concentration of tellurium(IV) taken, was measured by NaI(Tl) well- type scintillation counter. The calibration graph is linear in the ran ge 0.15-15 mu g of tellurium(IV) in a final volume of 30 ml. The detec tion limit of the method has been found to be 5 ng ml(-1) of tellurium . The interferences due to many ions were overcome by using aluminium hydroxide collection procedure. The method has been applied for the de termination of trace amounts of tellurium in copper metal, copper conc entrates and Sb-In alloy samples.