Tissue free water tritium separation from foodstuffs by azeotropic distillation

In this paper the tritium separation from tissue free water in foodstuffs by azeotropic distillation is described. Tritium in tissue water is assayed by liquid scintillation counting using well-established quenched correction method. The mean value of the tritium concentration in tissue water from foodstuffs is about 6-12 Bq/l very similar to the tritium mean concentration measured in the surface waters of the area where the samples have been collected (about 12 Bq/l. Therefore, the tritium content in the water fraction of the food samples can be considered in equilibrium with the local environmental water sources. The azeotropic distillation it is an accessible separation method which does not need a sophisticated and expansive distillation apparatus. It is a fast method of separation tissue free water from foodstuffs being very important in the surveillance activity of the environmental within nuclear electric plant. It is suitable for processing a small quantity of samples and for a production type facility when a large number of samples must be processed because the solvent can be purified and reused. The azeotropic distillation has some limits being used to separate water from samples with high content of water (85-90%) and simple a simple chemical structures as: vegetables, fruits, cereal, soil, vegetation. According to the results obtained, the organic substituents of milk, wine, meat (casein, lactose, milk fat, alcohol, esters) may enhance the chemisorption of tritium on through exchange organic hydrogen as -OH, -SH, -NH, -COOH with tritium. Also, the tissue water separation by azeotropic distillation is not complete and can not guarantee the absence of the vaporization isotope effect of the HTO/H2O system., However, the azeotropic distillation is the preferred method of the water extraction from food samples, which makes it useful for the tritium transfer from soil to foodstuffs. (authors)