Experimental study of suitable methods for measuring the radioactivity of 90Sr during its fast quantitation by extraction with dicarbollides

The measurement of activity of 90Sr during its fast isolation by extraction with cobalt dicarbollide and Slovafol 909 in a nitrobenzene-carbon tetrachloride mixed solvent and re-extraction with 0.15 M Chelaton IV at pH 10.2 was investigated. The use of a liquid scintillator allows the effect of the 90Y beta activity to be eliminated more efficiently than if the evaporation residue is measured with a solid scintillator. Traces of dicarbollide, nitrobenzene and CCl4 passed into the aqueous solution exert an unfavorable effect by shifting the spectral curve of the 90Sr+90Y beta radiation towards lower energies, the shift being dependent on the concentration of the above interferents in the aqueous phase. This effect can be eliminated by extracting the aqueous phase with the same volume of octyl alcohol or amyl acetate; while removing the organic interferents, this extraction brings about no apparent loss of strontium. (author). 3 tabs., 7 figs., 5 refs