Simultaneous determination of gross alpha/beta activities in water by liquid scintillation counting and its applications in the environmental monitoring.

Based on the standards of ISO11704-2018 and ASTM D7283-17, a method for simultaneous determination of gross alpha and gross beta activity concentrations in water by liquid scintillation counting (LSC) was established, which can be applied to various types of water samples in routine monitoring, such as drinking water, groundwater, geothermal water, seawater, and radioactive wastewater. The sample's pH value and concentrated volume must be controlled to avoid quenching as much as possible. The validation tests show that the deviations of gross alpha and gross beta activities can satisfy quality control requirements in a wide range of activity ratios from 1:102 to 67:1. For the actual samples, the measurement results of the LSC method are in good agreement with those of the thick source method, in which the relative deviations of gross alpha and gross beta are both less than 15% for these two methods. Moreover, the LSC method performs better in detection limit and has a simpler pretreatment process than the thick source method.