Objectif The method for determination of acid stable amino acids should be optimised during a series of intercomparisons. For tryptophan it should be agreed which method should be used, it should likewise be optimised and described.Four reference materials; 'mixed pig feed', 'low fat fish meal', 'soya been meal' and 'skim milk powder' should be prepared and certified.A method for determination of 16 acid stable amino acids have been optimised and tested first under DG VI and later under DG XII, BCR and SMT. After hydrolysis with strong acid the liberated amino acids are separated by ion-exchange chromatography and determined by post column reaction with ninhydrin. The method is proposed as a candidate community method.The amino acid tryptophan is acid labile and require a different sample preparation. A method including a basic hydrolysis with barium hydroxide at 110 oC for 20 hours has been developed. Tryptophan is measured using reversed phase HPLC with fluorimetric detection. The method has been tested during several intercomparisons, and is now proposed as a community method.Four reference materials: CRM 117: Mixed pig feed, CRM 118: Low fat fishmeal, CRM 119: Soya been meal and CRM 120: Skim milk powder, have been produced. Their homogeneity and stability have been studied and found satisfactory. The certification exercises have been carried out successfully for both methods. The Scientific Evaluation Group has not yet accepted the certification report although it has been modified several times according to their amendments. The stability of one of the materials is currently doubted because the stability studies were conducted in 1991-1993.The materials are not yet certified and it is questionable when they will be certified if they ever will be.BackgroundCommunity legislation (Directive 77/101/EEC and 79/373/EEC) obliges the declaration of certain amino acids in feeds for some animals. Lysine for pig feed and methionine for poultry feed, apart from this cystein, threonine and tryptophan is also covered by the legislation.The method used for determination of acid stable amino acids is a well-known method firstly described by More and Stein in 1951. It is based on ion-exchange chromatography and post column colour reaction with ninhydrin. Although the method is well known it needed some adjustments and streamlining especially in the sample preparation part.Tryptophan is acid labile, therefor alkaline conditions is used in the hydrolysis step of the sample preparation. Tryptophan is determined using several different chromato-graphic methods. The results obtained were known to vary, it was believed that the hydrolytic step should be optimised.No reference materials are available for measurement of these amino acids. Champ scientifique engineering and technologymaterials engineeringcolorsnatural scienceschemical sciencesinorganic chemistryalkaline earth metalsnatural scienceschemical sciencesorganic chemistryaminesagricultural sciencesanimal and dairy sciencedomestic animalsanimal husbandryanimal feed Programme(s) FP3-MAT - Specific research and technological development programme (EEC) in the field of measurements and testing, 1990-1994 Thème(s) Data not available Appel à propositions Data not available Régime de financement CSC - Cost-sharing contracts Coordinateur National Institute of Animal Science Contribution de l’UE Aucune donnée Adresse Foulum 8830 Tjele Danemark Voir sur la carte Coût total Aucune donnée
