Effect of analytical factors on the determination of gross alpha/beta activity in drinking water using liquid scintillation counting

A method for the determination of gross alpha and beta activity concentrations in drinking water samples was established using liquid scintillation counting (LSC) through a series of batch experiments on water samples spiked with 241Am and 90Sr/90Y. Counting windows were set to cover the full energy spectrum. α/β discrimination was investigated considering the use of calibration sources, spillover, and additional factors (e.g. scintillation cocktail type, acidic media, pH, sample-to-cocktail volume ratio) and was optimized. The optimized Pulse Shape Analysis value was set to 120 (τα + τβ = 5.511%). The impact of the total dissolved solids and sample-to-scintillation liquid volume ratio on counting efficiency was investigated. After optimization, the gross alpha and beta counting efficiencies were 26.6% and 37.6%, respectively. The measurement results demonstrated good agreement between the values obtained by LSC and the solid scintillation counting.