Standardization of a 85Sr solution by three methods

► The 85Sr solution activity was measured in the liquid scintillation counters. ► The dead times of the counters were longer than the lifetime of 85Rb excited level. ► Unregistered pulses from delayed transition caused an incorrect 85Sr standardization. ► The probability of no-registration of these pulses has been defined. ► The 85Sr solution activity calculated considering this probability was correct.