ISO INTERNATIONAL STANDARD 14891 IDF 185 First edition 2002-03-01 Milk and milk products Determination of nitrogen content Routine method using combustion according to the Dumas principle LaitetproduitslaitiersDeterminationdelateneurenazoteMethode pratiqueparcombustionselonleprincipedeDumas Reference numbers A ISO14891:2002(E) ISO IDF 185:2002(E) @ ISO and IDF 2002 HS unde Not for Resale ISO 14891:2002(E) IDF 185:2002(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this any liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by IsO member bodies and IDF national ?ISOandIDF2002 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic ISO copyright office International Dairy Federation Case postale 56. CH-1211 Geneva 20 41SquareVergote·B-1030Brussels Tel. + 41 22 749 01 11 Tel. + 32 2 733 98 88 Fax + 41 22 749 09 47 Fax + 32 2733 0413 E-mail copyright@iso.ch E-mail info@fil-idf.org Web www.iso.ch Web www.fil-idf.org Printed in Switzerland @ISOandIDF2002-All rightsreserved itted without license from IHS Not for Resale ISO 14891:2002(E) IDF 185:2002(E) Contents Page Foreword. .iv, vi 1 Scope 2 Normative referenc 3 Term and definition . 4 Principle.. 5 Reagents 6 Apparatus 7 Sampling 8 Preparation of test sample. 8.1 General.... 8.2 Liquid test samples. 9 Procedure. 9.1 General. 9.2 Testportion 9.3 Control of oxygen demand. 9.4 Calibration.... 9.5 Determination. 9.6 Detection and integration 10 Calculation and expression of results. 10.1 Calculation. 10.2 Expression of results 11 Precision. 11.1 Interlaboratory test 11.2 Repeatability 11.3 Reproducibility. 12 Test report. Annex A (informative) Flowchart for the basic design of a Dumas apparatus. .8 Annex B (informative) Schemes of suitable types of Dumas apparatus... Annex C (informative) Equipment calibration . Annex D (informative) Comparison of results using the Dumas method with those obtained by the Kjeldahl method... 13 Bibliography. 14 ili Copyright Interna se from IHS Not for Resal