The possibility of the use of chlorinated cobalt dicarbolide, H+C4B18H15Cl7Co−, it nitrobenzene for the selective extraction of137Cs from mixtures of95Zr−95Nb,106Ru-106Rh and144Ce was studied. The effect of aqueous phase acidity on the distribution ratio of Cs, Ru and Zr as well as the effect of the
amount of isotopic and non-isotopic carriers of alkali metals on the distribution ratio were determined. Separation factors
for cesium from ruthenium, zirconium and cerium were calculated, all being extracted from nitric acid solutions. The efficiency
of cesium separation was verified by gamma-spectrometry.