Rapid determination of ⁹⁹Tc in water samples using Ti(OH)₃-TcO₂ co-precipitation and TK200 resin by liquid scintillation counting

A novel method for the determination of 99Tc in water samples was developed using stable Re as a chemical yield tracer and TiCl3 as a reducing agent. The influences of several experimental parameters, including TiCl3 concentration, HCl concentration and reaction time, on the reduction of TcO4− and ReO4− as well as Ti(OH)3-TcO2-ReO2 co-precipitation were investigated.

Tc(VII) and Re(VII) retained on TK200 resin were effectively eluted by 5 mL of 1 mol/L NH4SCN, which can be directly mixed with the scintillation cocktail for liquid scintillation counting. The results show that the chemical behaviors of Tc and Re are very consistent in the whole procedure. The decontamination factors of potential interferences from β-emitting nuclides mainly released from nuclear fuel reprocessing plants were also evaluated, and the minimum detectable activity concentration was calculated to be 0.08 Bq/L for 99Tc in water samples with a counting time of 2 h.