Determination of potassium traces in foodstuffs by natural 40K radiation

After the Chernobyl accident in April 1986, Mexico imported from one European country a shipment of 28,000 tons of milk powder contaminated with the fission product 137Cs. Since then, the local authorities of Public Health have established as a compulsory condition to obtain through gamma-spectroscopy a certificate of no radioactive contamination either to imported or exported foodstuffs. But at the same time, the absence of long-lived, gamma-emitters fission products is certified, it is also possible to find the concentration of the important trace element K in foodstuffs, by the peak of 1461 keV from 40K, invariably present in the gamma-spectra. Taking advantage of the fact that it does not require any previous manipulation of the sample, this paper describes the general procedure in milk powder or any other foodstuff.