where A is the activity concentration of a particular nuclide in Bq/kg, Cn the net counts (background subtracted) in the corresponding photopeak, εγ is the absolute efficiency at photopeak energy, Pγ the gamma-ray emission probability corresponding to the photopeak energy, t the counting time in second and m the mass of soil sample in kg.
The minimum detectable activity (MDA) at the 95% confidence level was also determined, taking into account the background measurements as follows [19] and [20]