Determination of iodine in foodstuffs consumed in Libya using instrumental and radiochemical neutron activation analysis

Iodine was determined in foodstuffs consumed in Libya employing two modes of NAA. The first mode was instrumental using short-time irradiation with epithermal neutrons behind a Cd shield (EINAA). The other mode utilized short-time irradiation with the reactor-pile neutrons followed by radiochemical separation (RNAA). The radiochemical separation procedure was based on the alkaline-oxidative fusion of samples and extraction of elemental iodine into chloroform. Separation yield determined using the radiotracer 131I was within the range of 90 to 95 %. For quality control purposes, standard reference materials were analyzed in both modes employed. Using RNAA, a detection limit of about 1 ng g-1 could be obtained indicating superiority of the method in measuring ultra-trace levels of iodine. On the other hand, more than one order of magnitude higher detection limit did not allow sufficiently accurate determination of iodine in Libyan foodstuffs using EINAA. (author)