Activation analysis of selenium in organic samples,through selenium-77m,on a pre-separation basis

A method is described to separate trace amounts of selenium in organic samples without using a carrier, based on the adsorption on active carbon filters of the complex formed with APDC at pH 1.5. The separation is made prior to the neutron irradiation and the correction for selenium in the reagents performed by the irradiation of a blank. The method has been successfully used in fodder samples as well as some other organic reference materials, using a fast pneumatic transfersystem, which takes the samples from the irradiation position to the counting position in 3s, with the only limitation of the thermal neutron flux available, 4.7·10¹¹ cm^–2·s^–1. Detection limits of 0.1 g are obtained under these experimental conditions.