To evaluate the alpha procedure recovery,1 mL of 232U and 229Th
certified solutions with well-known activity concentration values
(42.4 0.84 Bq L1 and 61.0 1.71 Bq L1, respectively) were used,
both provided by Ciemat (Centro de Investigaciones Energéticas,
Medioambientales y Tecnológicas) (Madrid, Spain).