Determination of 90Sr in contaminated environmental samples by tuneable bandpass dynamic reaction cell ICP-MS

A rapid method for the extraction and determination of Sr-90 in natural water, plant and sediment samples was developed using extraction chromatography and dynamic reaction cell ICP-MS, with O-2 as a reaction gas. While isobaric interference from the stable isotope Zr-90 was efficiently removed by this method, interferences produced from in-cell reactions with Fe+ and Ni+ required suppression by tuneable bandpass, and in sediments, additional chromatographic separation. Method detection limits were 0.1 pg g(-1) (0.5 Bq g(-1)), 0.04 pg g(-1) (0.2 Bq g(-1)), and 3 pg L-1 (5 Bq L-1) for sediments, plant and water samples, respectively, and Sr-90 concentrations determined by ICP-MS were in good agreement with activities determined by Cerenkov counting and with certified reference values. While mass spectrometric determination does not rival detection limits achievable by radiometric counting, radiometric determination of Sr-90, a pure beta-emitter, is hindered by long analysis times (several weeks); the comparatively fast analysis achieved via ICP-MS enables same-day preparation and analysis of samples, making this an important technique for the environmental monitoring of areas contaminated by radioactivity.