DETERMINATION OF TC-99 IN BENTONITE CLAY SAMPLES USING INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

A method was developed for the determination of Tc-99 at low concentra tions in clay samples. The chemical treatment of the samples prior to chemical separation and analysis comprised leaching with sulphuric aci d/sodium bromate. After leaching, pertechnetate was extracted with Ala mine-336/chloroform and then back-extracted into nitric acid. Detectio n was carried out using inductively coupled plasma mass spectrometry, ICP-MS. The instrumental detection limit was 0.45 pg/mL, which corresp onds to 0.28 mBq/mL. With the use of a desolvating nebuliser, the dete ction limit was lowered by about a factor of five. The results were co mpared with a method using radiometric detection.