Trace determination of tellurium using liquid scintillation and Cerenkov counting

A sensitive and selective radiometric method for the determination of trace levels of tellurium is described. The method is based on the radiodisplacement of Cd(II) from a bis(diethyldithiocarbamato)cadmium-115m(II) complex by Te(IV) at pH 3.3. The activity of the displaced radiocadmium, which is proportional to the amount of Te(IV) taken, was measured by liquid scintillation counting (LSC) and Cerenkov counting. The counting efficiency of LSC and Cerenkov counting was found to be 130% and 36%, respectively. The calibration graph was linear in the range 0.05-15 μg of tellurium in a final aqueous volume of 10 ml. The methods allowed the determination of tellurium at levels down to 0.05 μg for LSC and 0.1 μg for Cerenkov counting in a final volume of 40 ml. Quenching studies were carried out on the basis of the spetral index of the sample (SIS), which is a very sensitive quench indicating parameter, and the results clearly revealed the absence of colour and chemical quenching. The influence of foreign ions on the radiodisplacement reaction was studied and was easily eliminated by adopting an aluminium hydroxide collection procedure and by using proper masking agents. The method was successfully applied to the determination of tellurium in copper metal, copper concentrates, Sb-In alloy and cadmium oxide samples.