Preparation of MnO₂ coated fibers for gamma spectrometric measurements - A comparison of four practical approaches

Highlights: • Radium is a powerful environmental tracer in aquatic systems. • Radium extraction from low-level water samples by adsorption onto MnO₂ fiber. • Further sample preparation requires straightforward practical approach. • Evaluation of four approaches based on practical effort vs. data reproducibility. • Study revealed compaction of fiber incl. adhesive as most practical method. - Abstract: The analysis of natural radium-in-water activity concentrations is for two reasons of general interest: (1) radium in natural waters may pose a problem with regard to radiation protection and (2) radium isotopes in natural waters can be used as environmental tracers in hydrological studies. A state-of-the-art method for radium extraction from (generally large) water sample volumes is radium adsorption onto MnO₂ coated acrylic fibers. In our study we comparatively evaluated four methodical approaches for post-extraction preparation of the fiber to allow gamma spectrometric measurements. The methods included (1) straightforward measurement of the loose fiber, (2) compressing the fiber after mixing it with an adhesive, (3) combustion of the fiber and embedding the ash in candlewax, and (4) leaching of the fiber and embedding the resulting precipitate in candlewax. The aim of the study was to compare the advantages and disadvantages of the four preparation approaches with respect to their individual practicability. Even though the methodical fiber preparation approaches have been suggested in the literature before (as cited in this paper), results of their direct practical comparison have not been presented yet. Our study revealed that balancing practical sample preparation effort against data reproducibility suggests a measurement of the compressed fiber applying an adhesive to be the preferable approach.