Determination of tin in indium by neutron activation with pre-irradiation separation

Prior to irradiation tin is separated from a 1g indium sample by iodide extraction followed by precipitation with Pb/OH/2. The amounts of tin introduced as contaminant before pre-irradiation treatment do not exceed 0.1 μg in most cases. After irradiation in a thermal neutron flux of 5.1013 n.cm-2.s-1 and suitable cooling tin is extracted substoichiometrically with benzoylphenylhydroxyl amine. The content of tin is determined on the basis of the 158 keV photopeak of sup(117m)Sn in the γ-spectrum. Other photopeaks appearing in the spectrum indicate the presence of various isotopes, it is not possible to determine tin on the basis of counting 121Sn γ-rays. The lower limit of determination is 0.2 ppm. (T.G.)