The determination of technetium-99 in urine

Abstract

A method has been developed for the routine radiochemical analysis of technetium-99 in human urine. The excreted technetium is coprecipitated from a 200 mL urine sample with CuS. Valence state adjustments are performed with K2S2O8. The precipitate is dissolved in ammoniacal peroxide and, after the Cu(II) is removed by ion exchange, the Tc-99 is extracted with 2-butanone (MEK). Subsequent evaporation of the organic solvent gives an essentially weightless source that if counted with a gas proportional counter will give a better limit of detection than liquid scintillation methods. The recovery of Tc-99 using this procedure is 80% (σ = 4%) and the limit of detection is 20 mBq (0.6 pCi) at the 95% confidence level for a routine sample – counting time 20 minutes, counting efficiency 24%, ambient background 1.3 counts per minute (cpm).