ABSTRACT
A rapid analytical method for quantifying 90Sr in infant formula prior to secular equilibrium is presented. The approach is dependent on the use of two separations of 90Sr from 90Y, with the first providing an 90Y ingrowth start point and the second providing an 90Y ingrowth end point. Data were obtained at activity concentrations of approximately 6 Bq/kg and 160 Bq/kg, the latter of which is representative of the US Food and Drug Administration (FDA) Derived Intervention Levels (DIL). Experiments were designed to collect data from ingrowth periods ranging from 16 h to 2 weeks. Activities obtained with a separation interval as low as 16 h ranged from 92.7 to 109.4% of the known value. When 90Y ingrowth was allowed to occur for 24 h or longer, the activities ranged from 93.2 to 106.2% of the known value and the precision of this group improved from 5.2 to 3.1%. The limit of quantification (LOQ) was 0.5 Bq/kg using 250 g sample portions.
ABSTRACT
Based on the original work of Rutherford (Radio-activity, 1905) and Bateman (Proc Camb Philos Soc 15:423-427, 1910), the authors designed two schemes consisting of explicit equations as simple methods for accurately obtaining activity of 90Sr and 90Y before they reach secular equilibrium. Application of the methods to the 90Sr/90Y system where 90Sr and 90Y are not in equilibrium will substantially reduce the time needed for determining activity of 90Sr because neither sequential measurements of 90Sr or 90Y (up to about 2 weeks) nor waiting for 90Sr and 90Y to reach equilibrium (more than 3 weeks) will be needed. We also implemented the explicit equations for decay/ingrowth correction of progeny's activity and applied them to the 95Zr/95Nb system. Using the equations, the authors corrected activity concentrations of 95Nb to a designated reference time from the activity concentrations measured from samples at different times, for instance, 2, 8, 15, and 29 days after a reference time. During those measurement times, 95Nb and 95Zr were not in equilibrium. The corrected 95Nb activity concentrations were within an accuracy of - 10%.
ABSTRACT
A portable CeBr3 based gamma-ray detection system was designed and built for rapid turnaround, high throughput, real-time, and in situ sample analysis. The new technique allows automated data transmission from the field unit to a central laboratory controller to ensure laboratory quality of the data collected by field users without gamma-ray spectroscopy expertise. The method validation data indicates that the system's data quality objectives are adequate for radiological or nuclear emergency response or targeted surveillance programs where gamma-ray analysis is needed.
