Comparative Study of Uranium and Thorium Content of Some Selected Nigerian and Nigerien Cereals Using Neutron Activation Analysis.

Abstract

The need to know the level of contamination of radioactive elements, especially uranium and thorium, in the common foods we eat is highly significant. In this study, 7 food samples, mainly cereals were collected from some parts of Katsina State in Nigeria and Maradi in Niger Republic. The cereals sampled were beans, millet and sorghum. Nigerian rice was analyzed as the seventh sample because there is no commercially grown rice in Niger Republic for comparison. The sampled cereals were analyzed for Uranium and Thorium content. The work was performed with both short and long irradiation protocols of Instrumental Neutron Activation Analysis (INAA) at the Nigerian Research Reactor-1 (NIRR-1) of the Center for Energy Research and Training (CERT) Ahmadu Bello University, Zaria- Nigeria. INAA was chosen due to its advantages over other analytical techniques. Thorium was detected at concentrations ranging from 0.3 to 0.6 μgg^-1 while Uranium concentrations were below detection limit in all the seven samples. Among the samples, Nigerian millet has the highest concentration (0.6 μgg^-1) of Thorium, while Nigerian beans and Nigerian rice have the lowest (0.3 μgg^-1). Generally, with the exception of Nigerien sorghum, Nigerian cereals have higher concentrations of Thorium. The results compare favorably with those of other workers using different versions of INAA on related cereals. Quality control and Quality Assurance of the method was tested by analyzing an analytical quality control service (AQCS) reference material (lichen) from International Atomic Energy Agency (IAEA).

Keywords: Key words: Uranium, Thorium, neutron activation analysis, Cereals, Katsina, Maradi.