Preconcentration and separation of 99Tc in groundwater by using TEVA resin

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.

Automatic multicommuted flow systems applied in sample treatment for radionuclide determination in biological and environmental analysis

The presence of artificial and natural radioactivity in the environment is currently a topic of great relevance and ecological interest, even in human health issue, due to the increase of different anthropogenic activities. The use of multicommuted flow analysis techniques (e.g. Multi-Syringe Flow Injection Analysis - MSFIA, Lab-On-Valve - LOV and Lab-In-Syringe - LIS) has allowed the automation of radiochemical procedures to separate and preconcentrate radionuclides in environmental and biological samples. In comparison with the manual approach commonly used in routine analysis for radioactivity monitoring, the automation has enabled the development of highly reproducible methodologies with a great analysis frequency. Moreover, during the analytical procedure, the intervention of the analyst is drastically reduced, minimizing the radiological risk. The automation also offers significant advantages such as minimum consumption of time and reagents, reducing the cost and the generation of waste, contributing to the green chemistry. In this review, several multicommuted flow analysis techniques (MSFIA, LOV and LIS) reported in the last decade applied for the development of automatic sample treatment methodologies, used to separate, preconcentrate and quantify ⁹⁰Sr, ⁹⁹Tc, natural U and ²²⁶Ra in biological and environmental samples are described and critically compared.