Radiochemical determination of Caesium-137, strontium-89,90 and barium-140 in milk and bone ash

Abstract

A method for the determination of radiocaesium, radiostrontium, radiobarium in milk and bone ash is described. An alkaline fusion of ash followed by leaching with water provides for the preliminary separation of radiocaesium. After dissolution of leaching residue in hydrochloric acid and sorption on Dowex 50 W, X-8, radioyttrium (rare earths fission products), magnesium and calcium are eluted with 1.0 M ammonium lactate, pH 7.5. Radiostrontium, radiobarium and radium are separated by elution with 0.15 M ammonium citrate, pH 7.5. 137Cs is isolated as Cs-dipicrylaminate, 89Sr/90Sr as SrCO3, 140Ba as BaCO3 and counted on a low-background beta-counter. For determined radionuclides the average chemical yields amount to ∼ 80%. The limits of detection for 137Cs, 90Sr, 140Ba are ∼ 0.02 pCi/g with a 10 g sample of milk ash and ∼ 0.04 pCi/g with a 4 g sample of bone ash, respectively.