IMPROVEMENTS IN THE METHOD OF SR-90 EXTRACTION FROM ENVIRONMENTAL-SAMPLES WITH DICYCLOHEXYL-18-CROWN-6

Yields in each step of a chemical procedure to isolate strontium from environmental samples for radiometric determination of Sr-90 were dete rmined. The method is based on nitric acid leaching followed by chroma tographic extraction of strontium and radiometric determination of Sr- 90. Dicyclohexyl-18-crown-6 in tetrachloroethane, which is held as a l iquid in pores of styrene-divinyl benzene beads, serves as the extract ant. A key step is desorption from the chromatographic column by use o f hot water, which has been optimized to recover 90 % of the strontium . In conjunction with advanced radiometry, measuring Sr-90 activities of the order of 0.1 Bq per sample is expected to be feasible.