Neutron activation analysis determination of trace amounts of mercury in selected foodstuffs

Neutron activation analysis was used for the determination of trace amounts of mercury in powdered milk, flour, coffee, rice and tea. The results of the determination were compared with the photometric determination of mercury using dithizone. Four wet mineralization procedures were also assessed with regard to mercury release during sample destruction. Following thermal neutron irradiation and the addition of a carrier the samples were mineralized with a mixture of H2SO4+HClO4+HNO3; the mineralization product was diluted and extracted by a substoichiometric amount of dithizone-chloroform solution. The activity of 197Hg in the organic phase was measured with a NaI(Tl) crystal. The determination threshold was found to be 0.003 μg Hg at a mean error of 15%. (B.S.)