Determination of Theobromine in Animal Feeding Stuffs

mal Feeding Stuffs R. S. HArruLL, I. MTLNER AND V. STANWAY County Analyst’s Department, Martin Strcet, Stofford, 5T16 2LG A method is described for the determination of th€obromine in animal feeding stuffs. The sample is extracted with hot water and, after clarification, examined b,y High Performance Liquid Chromato$aphy using benzoic acid as an internal standard. Recovery of added theobromine is of the order of 90 per cent., down to a levet of about 20 mg/kg in the feeding stuff. Under the provisions of The Fertilisers and Feeding Stuffs (Amendment) R.egulations 1976 therc are prescribed maximum limits of theobromine of 300 mg/kg in whole feeding stuffs and 700 mg/kg in feeding stuffs for adult cattle, but these Regulations do not include a prescribed method of analysis for theobromine. It was found that theobromine was readily exhacted from animal feeding stuffs by digestion at boiling point with water and that such an extract, after clalification with Carrez Reagents (zinc and ferrocyanide), was suitable for direct injection on to an HPLC column of Partisil P x S 10/25 ODS with u.v. detection at 272 nm. The main problem encountered was the swelling of the sample portion due to t