Analysis of inorganic selenium species using HPLC and ICP-MS for monitoring the mobility of selenium in engineered barriers of nuclear waste repositories

The interconversions of Se species in aqueous suspensions of bentonite were studied at various pH by using HPLC, ion-pair reversed-phase and anion-exchange chromatographies, and ICP-MS. Some chromatographic parameters were optimized to improve the separation of the species. The limit of Se detection was determined and the linearity of calibration curves was verified. In alkaline medium, a considerable amount of selenite in contact with bentonite was oxidized to selenate within two weeks. As the retention of selenate in the barrier is lower than that of selenite, Se could spread easily