ISO INTERNATIONAL STANDARD 6655 First edition 1997-08-01 ANSI Internat Doc Sed Animal feeding stuffs Determination of soluble nitrogen content after treatment with pepsin in dilute hydrochloric acid Aliments des animaux - Determination de la teneur en azote soluble apres traitement avec de la pepsine dans I'acide chlorhydrique dilue ISO Reference number ISO 6655:1997(E) No reproduction or networking permitted without license from IHS Not for Resale ISO6655:1997(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO member bodies). The work of preparing International Standards is normally carried out through IsO technical committees. Each member body interested in a subject for which a technical committee has been established has liaison with IsO, also take part in the work. isO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Internationai Standard ISO 6655 was prepared by Technical Committee ISO/TC 34, Agricultural food products, SubcommitteeS10,Animalfeedingstuffs. Annex A forms an integral part of this International Standard. Annexes B and C are for information only. @1SO1997 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced microfilm, without permission in writing from the publisher. InternationalOrganizationforStandardization Case postale 56 . CH-1211 Geneve 20 . Switzerland Internet [email protected] X.400 C=ch; a=400net; p=iso; 0=isocs; S=central Printed in Switzerland No reproduction or networking permitted without license from IHS Not for Resale ISO 6655:1997(E) INTERNATIONALSTANDARD ISO Animal feeding stuffs Determination of soluble nitrogen content after treatment with pepsin in dilute hydrochloric acid Scope This International Standard specifies a method for the determination of the soluble nitrogen content of anima! feeding stuffs after treatment with pepsin in dilute hydrochloric acid. This method does not distinguish between protein nitrogen and non-protein nitrogen. NOTES 1 The values obtained on using this method have no direct connection with digestibility in vivo. method. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and IsO maintain registers of currently valid International Standards. IsO5983:1997',Animalfeeding stuffs-Determination of nitrogen content and calculation of crudeprotein content--- Kjeldahlmethod. IsO6498:1983,Animalfeedingstuffs-Preparationoftestsamples. 3 Principle Incubation of the sample for 48 h at 4o C in a solution of pepsin in dilute hydrochloric acid. Filtration of the suspension and determination of the nitrogen content of either the filtrate or the residue determination of the nitrogen content of the sample as well, in accordance with Iso 5983. 4 Reagents Use only reagents of recognized analytical grade, and distilled or demineralized water or water of at least equivalent purity. The reagents (except the standard materials) shall be practically free from nitrogenous compounds. 1To be published. (Revision of ISO 5983:1979) No reproduction or networking permited without license from IHS Not for Resale