The extraction of le3 Ru, 133 Ba, 137 Cs,14, Ce, 152 Eu in addition to "Na has been studied using six crown compounds of different cavity sizes and substitutions in nitrobenzene. Ruthenium is not extracted and thus can be separated in picrate media from other nuclides by applying methanol in the aqueous phase and picric acid in the organic phase. Barium is extracted quantitatively with dicyclohexyl-18-crown-6 independent of the organic solvents and can be separated selectively in non-polar solvents.