where:
CS = Counts per second obtained from the sample;
CB = Counts per second obtained from the background;
WS = Foodstuff sample weight;
Det.Eff. = Detection Efficiency for 1461 keV γ rays in scintillation detector/100.
Branching ratio 40K decaying to 40Ar111000.11.
Then, concentration of elementary K (%) in foodstuff samples is simply obtained by the following equation: