(ISo 5510 International Standard INTE RNATIONAL ORGANIZATION FOR STANDARDIZATION MEKAYHAPOAHAR OPrAHM3AUMA IO CTAHAAPTW3AUMMORGANISATION INTE RNATIONALE DE NORMALISATION ANsI Internar Doc Sec! Animal feeding stuffs - Determination of available lysine Aliments des animaux -- Dosage de la lysine disponible First edition - 1984-11-15 Ref. No. 1SO 5510-1984 (E) UDC 636.087.1 : 543.544 : 547.466.46 ISO 5510-1984 (E) Price based on 5 pages Copyright International Organization for Standardization Not for Res Foreword Iso (the International Organization for Standardization) is a worldwide federation of national standards bodies (isO member bodies). The work of preparing Internationat Standards is normaily carried out through ISo technical committees. Each member body interested in a subject for which a technical committee has been established has mental and non-governmental, in liaison with Iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as. International Standards by the IsO Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 5510 was prepared by Technical Committee ISO/TC 34, Agricultural food products. International Organization for Standardization, 1984 Printed in Switzerland Copyright International Organization for Standardization NotforRes ISO 5510-1984 (E) INTERNATIONAL STANDARD Animal feeding stuffs --- Determination of available lysine Introduction purification, then hydrolysis with hydrochloric acid, separation of the non-available lysine by column chromatography, and Lysine in food products is .generally considered to be determination by spectrometry at 570 nm. assimilable when its terminal amino group (amino e) is not com- bined. This fraction of lysine can be determined because these 5 Reagents groups combine with 2,4-dinitrofluorobenzene. All the reagents shall be of recognized analytical grade. The 1 Scope and field of application waterused shall bedistilled water or water of at least equivalent purity. This International Standard specifies a method for the deter- mination of the avaitable lysine in animal feeding stuffs contain- 5.1 Diethyl ether, free from peroxides. ing animal or vegetable proteins. Compared with biological determination, the method does, 5.2 Sodium bicarbonate, 80 g/l solution. however, overestimate the amount of available lysine and care is necessary in interpreting the results. 5.3 2,4-Dinitrofluorobenzene (DNFB), ethanolic solution. Dissolve 0,15 ml of DNFB in 12 ml of 95 % (V/ V) ethanol. 2 References Prepare this solution at the time of use. Iso 5983, Animal feeding stuffs - Determination of nitrogen content and calculation of crude protein content. 5.4 Hydrochloric acid, approximately 6 mol/1 . ISO 6497, Animal feeding stuffs -- Sampling.1) Mix 1 volume of hydrochioric acid (020 = 1,19 g/ml) with Iso 6498, Animal feeding stuffs -- Preparation of test samples. 1 volume of water. 5.5 3 Definition Sodium citrate, buffer solution, pH 2,2 approximately. Successively dissolve in water available lysine: The quantity of lysine corresponding to the difference between the total lysine and the non-available lysine 21 g of citric acid monohydrate; determinedunderthecondition pecified in this International Standard. 8 g of sodium hydroxide; It is expressed as a percentage by mass of the raw product. 16 ml of hydrochloric acid (020 = 1,19 g/ml); 4 Principle 0,1 ml of octanoic (caprylic) acid; Hydrolysis with hydrochioric acid of a ground test portion, 20 ml of thiodiglycol; foilowed by separation of the total lysine by column 3 ml of a 30 % (V/ V) aqueous solution of polyoxyethylene 570 nm. dodecyt ether with approximately 23 molecules of oxy- ethylene.2) Reaction of a second ground test portion with an ethanolic solution of 2,4-dinitrofluorobenzene in an atkaline medium, Dilute to 1 0