Determination of 41Ca with LSC and AMS: method development, modifications and applications
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Despite the emission of only low energy Auger electrons (ca. 3.6 keV) and the difficulty of obtaining a certified standard, Liquid scintillation counting (LSC) determinations are still reasonable options for a radioanalytical laboratory involved in nuclear installation decommission. Besides, accelerator mass spectrometry (AMS), being the most sensitive analytical technique not only for 41Ca, is gaining increasingly broader accessibility and applicability. Herein, we present a radiochemical separation procedure developed for 41Ca determination with LSC and AMS in varying materials (i.e. water, concrete, sediment, soil, and biota). The radioanalytical isolation consists of anion exchange and extraction chromatography as well as carbonate precipitation and recrystallization from organic solvents. Thereby, interfering radionuclides as 55Fe, 60Co, 152Eu, U or actinides are removed with decontamination factors of 102–104. Quench curves for determining the measurement efficiency is generated with a 41Ca solution gained from the 41Ca/40Ca certified reference material ERM-AE701. In routine application the procedure is characterized by chemical yields of 67–86 %, measurement efficiencies of 1–10 % and detection limits of 0.05 Bq g−1 and 0.3 Bq L−1. Aliquots of the digestion solutions of LSC can be easily converted into CaF2–AMS targets by successive oxsalate and fluoride precipitation. Pros and cons for both measurement techniques are addressed based on 41Ca results from LSC and AMS for the same material.
Keywords41Ca Radiochemical separation Liquid scintillation counting (LSC) Accelerator mass spectrometry (AMS) Method comparison
The DREAMS accelerator team is highly appreciated for assistance during AMS beamtime.
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