A simple non-distillation method for the estimation of Ru-106 in urine

A simple method has been developed for estimating Ru-106 in urine. Urine samples spiked with 3-50 Bq of Ru-106 and 200 micrograms of ruthenium carrier were initially oxidized using an HNO3-H2O2 mixture. Attempts to recover ruthenium by various preconcentration methods after the initial oxidation resulted in recoveries ranging from 10-54% depending on the experimental conditions. For near quantitative recoveries, the organic matter in urine was completely destroyed by wet ashing with HNO3-H2O2 (method A) or HNO3-H2O2 followed by H2SO4 treatment (method B). The ruthenium was oxidized to RuO4 using potassium periodate and allowed to react in situ with polyethylene powder. The polyethylene powder was separated, washed and its beta activity was counted. The recovery of ruthenium was 86.9 +/- 4.6% (RSD 5.3%) in method A; and 94.4 +/- 2.6% (RSD 2.8%) in method B. The minimum detection limit achieved was 0.59 Bq/dm3. Interferences due to Cs-137 and Sr-90 were studied.