Fractionation analysis of iodine in bovine milk by preconcentration neutron activation analysis

Iodine is an essential trace element for human beings. The main source of iodine is generally food items such as fish and milk. Either the lack or the excess of iodine can cause health problems. There exists an increasing interest in the determination of total iodine as well as various species of iodine in milk. We have developed an epithermal neutron activation analysis method with a Compton suppression (ENAA–CS) counting system for the determination of ng mL−1 levels of iodine. We have also employed chemical separation methods prior to ENAA–CS to measure the fraction-specific concentrations of iodine in bovine milk. We have measured the following iodine concentrations in homogenized milk (3.25%milk fat): 0.48 ± 0.02 μg mL−1 of total iodine, 0.020 ± 0.003 μg mL−1 of lipid-bound iodine, 0.039 ± 0.002, 0.019 ± 0.002 and 0.021 ± 0.004 μg mL−1 of protein-bound iodine depending on the protein separation method and 0.45 ± 0.02 μg mL−1 of inorganic species.