Expanded uncertainties of preconcentration neutron activation measurements of extractable organo-chlorine, bromine and iodine compounds in bovine milk lipids

Milk is known to contain organohalogen compounds. A mixture of hexane and isopropanol was used to extract lipids from bovine milk and neutron activation analysis (NAA) was employed to measure extractable organohalogens in the lipids. The samples were irradiated in a neutron flux of 2.5 × 1011 cm2 s-1 for 10 min, allowed to decay for 2 min, and counted for 10 min. Uncertainties associated with the preconcentration NAA measurements were investigated in detail. The mass fractions of halogens in mg kg-1 and their relative expanded uncertainties in percent in bovine milk lipids were: 32 (8.4 %), 2.65 (9.8 %) and 0.211 (6.6 %) for Cl, Br and I, respectively. (author)