Liquid scintillation counter calibration approach for 90Sr detection and testing performance of TK100 resin

90Sr detection efficiency determination was applied for liquid scintillation counting (LSC) by computing a model for the relation between detection efficiency and the time passed since radiochemical separation. This allowed more flexibility in analysis times after separation as the model accounts for 90Y in-growth. Establishment of secular equilibrium was therefore not required for LSC measurements. In addition, this approach increases counting efficiency compared to classical ones as both 90Sr and 90Y spectrums are used. This in turn has a positive impact on minimum detectable activity. The method was validated using proficiency test samples for both Čerenkov radiation measurement and scintillation cocktail measurement. Commonly used extraction material Sr-resin was compared to alternative, TK100 resin. Inductively-coupled plasma mass spectrometry measurements for recovery determination showed limitations for TK100 usage due to incomplete Sr retention on the resin. Limitations were further confirmed by LSC activity measurements. © 2019 Elsevier Lt