The Determination of Selenium in Animal Feeding Stuffs

imal Feerling Stuffs J. H. Harumcn eNo D. TAYLoR Dr Bemard Dyer & Partners (1948) Ltd, 20 Eastcheap, London E.C.3 A method is described for determination of low levels of selenium, which are required to be declared by the Feediry Stuffs Regulations of 1976, and which is based on wet ashing the finely gound sample followed by conversion to s-nitropiazselenol which is detected by gas chromatography using an electroD capture detectol. The Feeding Stuffs Regulations 19761 now require a declaration of total selenium when selenium has been added in &e course of the preparation of a compound animal feeding stuff. A method is therefore required for the determination of low levels of selenium in feeding stuffs, the addition declared by compounders being usually in the neighbourhood of 0’1 part per million. The method initially employed for the determination oflow levels of selenium in plant materials and widely used in the early investigations followed the method recommended for selenium in effiuentsz and was based on the reduc- tion of selenious acid to selenium by ascorbic acid or sulphur dioxide, and assessment of the reddish coloured suspensions obtained against suitably prepared standa