Determination of 210Pb and 210Po in soil or rock samples containing refractory matrices

A new method has been developed for determination of Pb-210 and Po-210 in soil or rock samples containing refractory matrices. The samples were first fused with Na2CO3 and Na2O2 at 600 degrees C for pre-treatment and then Pb-210 and Po-210 were sequentially leached out at 200-250 degrees C with HNO3 + HF, HClO4 and HCl. About 10% of the leaching solution was used for Po-101 determination, carried out by spontaneous deposition of polonium on a silver disc from a weakly acidic solution that contained hydroxylamine hydrochloride, sodium citrate and Po-209 tracer, measurement being made by alpha-spectrometry. The remains of the leaching solution were used for determination of Pb-210, conducted by precipitation as sulphate, purification with Na2S as PbS in 6 M ammonium acetate, separation from alpha-emitters by an anion-exchange resin column, source preparation as PbSO4, and measurement with a beta-counter. The procedure has been checked with two certified IAEA reference materials, showing good agreement with the recommended values. The lower limits of detection for 1 g of analysed soil or rock samples were found to be 0.75 Bq kg(-1) for Po-210 and 2.2 Bq kg(-1) for Pb-210. A variety of solid sample species analysed through use of the procedure gave average yields of 90.0 + 9.8% for Po-210 and 88.4 + 7.1 % for Pb-210. (c) 2006 Elsevier Ltd. All rights reserved.