ISO INTERNATIONAL STANDARD 20921 First edition 2019-02 Textiles Determination of stable nitrogen isotope ratio in cotton fibres Textiles - Détermination du rapport isotopique stable de I'azote dans les fibres de coton Reference number IS0 20921:2019(E) so @IS02019 IS0 20921:2019(E) COPYRIGHTPROTECTEDDOCUMENT @ ISO 2019 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either IsO at the address below or Iso's member body in the country of the requester. ISO copyright office CP 401 : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +4122 749 0111 Fax: +41 22 749 09 47 Email: copyright@iso.org Website: www.iso.org Published in Switzerland ii @ IS0 2019 - All rights reserved IS0 20921:2019(E) Contents Page Foreword ..iv Introduction. ..V 1 Scope. ..1 2 Normative references ..1 3 Terms and definitions 4 Principle ..2 5 Reagent. .2 6 Apparatus ..2 7 Preparation .3 7.1 Sampling of test specimen .3 7.2 Pre-treatment of test specimen .3 8 Test procedure. .3 8.1 Weighing of aliquot .3 8.1.1 Determination of weighing amount needed .3 8.1.2 General weighing procedure .3 8.2 Natural 15N abundance analysis 4 8.2.1 Instrumentation .4 8.2.2 General analytical procedure .4 9 Precision .5 10 Test report .5 Annex A (normative) Identification procedure of organic raw cotton fibres by using stable nitrogen isotope ratios. .6 Annex B (informative) Analytical results of cotton fibres of various origin and process stage ..8 Bibliography 10 @ IS0 2019 - All rights reserved iii