Anion exchange microsystems for radionuclides separation in nitric acid media
Résumé
The use of a centrifugal microfluidic platform is an alternative to classical chromatographic procedures for radiochemistry. The original design of the microfluidic platform has been thought to fasten and simplify the prototyping process with the use of a circular platform integrating four rectangular microchips made of thermoplastic. The microchips, dedicated to anion-exchange chromatographic separations, integrate a localized monolithic stationary phase as well as injection and collection reservoirs. An ion-exchange support with respect to the in-situ light-addressable process of elaboration is specifically designed to be incorporated as radiochemical sample preparation module in microsystem devices. Since their introduction in the early 1990s polymethacrylate monoliths have emerged as a powerful alternative for microscale separations or sample treatment. Their relatively simple implementation in columns with small internal diameters makes them particularly attractive for the new chromatographic challenges of complex matrices analysis and on-chip separations. Despite their relatively poor ion-exchange capacity due to their highly porous structure, their use as anion exchangers is of large interest for nuclear analysis as numerous separations are based on this process. A photopolymerized poly(ethylene glycol dimethacrylate-co-allyl methacrylate) monolith has been synthesized. It was then functionalized via a photografting process based on the ene-thiol click chemistry to give anion exchange properties to the monolith. The stationary phase has been optimized to improve its chromatographic performances especially regarding anion exchange chromatography. Synthesis and chromatographic results obtained with this monolith at macro scale and in COC micro-devices will be presented and discuss in term of reproducibility and robustness. Application to analysis of nuclear material will be presented.Thanks to their unique easy-to-use features, centrifugal microfluidic platforms are potential successful candidates for the downscaling of chromatographic separation and especially in the case of radioactive samples. Automation, multiplexing, easy integration in glove-boxes environment and low cost of maintenance are some advantages of the development of centrifugal microfluidic devices. Moreover the low amount of sample needed for the analysis allows the decrease of volume of effluents and the exposition of the operators to radiations during the analysis.
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