The simple radiochemical determination of 90Sr in environmental solid samples by solvent extraction

Determination of 90Sr in environmental solid samples is a challenging task because of the presence of so many other radionuclides in samples of interest. This problem was dealt with by radiochemical separation of strontium followed by yttrium separation and Cerenkov counting of the high-energy β-particle emissions of 90Y in order to quantitate 90Sr. In this work, an improved method is described for the determination of 90Sr in soil samples, through the separation of the daughter 90Y at equilibrium. The procedure is based on the HDEHP solvent extraction in combination with liquid scintillation spectrometry (LSS). A low background Quantulus has been optimized for low level counting of Cerenkov radiation emitted by the hard β-emitter 90Y. The analytical quality of the method has been checked by analyzing IAEA Soil-375 reference materials. The analytical method has also been successfully applied to the determination of 90Sr for moss-soil samples in inter-laboratory exercises through IAEA's ALMERA network. The chemical recovery for 90Y extraction ranged from 80 to 85% and the counting efficiency was 73% in the window 25-400 keV. (author)