Abstract
A radioanalytical method previously used for milk sample analyses was adopted for the measurement of strontium-90 in water, soil and biological samples. The method involved selective separation and successive counting of equilibrium quantities of yttrium-90, the daughter isotope of strontium-90. Yttrium-90 was extracted by tributyl phosphate (TBP) from nitrate medium and stripped by concentrated ammonia solution. Yttrium-90 was separated from possible iron by dissolving the gelatinous yttrium precipitate in nitric acid followed by yttrium oxalate precipitation using ammonium oxalate solution. After precipitation at pH 1-1.5, the chemical recovery of yttrium oxalate was 80 per cent. Yttrium oxalate was then re-dissolved in hydrochloric acid and measured by Cerenkov counting. This procedure was applied to the analysis of strontium-90 in certified reference materials and samples from the Riyadh region of Saudi Arabia (sandy soil and vegetation). Soil samples confirmed a degree of contamination from radioactive fallout in this region.