ISO INTERNATIONAL STANDARD 25475 First edition 2016-04-15 Fertilizers Determination of ammoniacal nitrogen Engrais - Détermination de I'azote ammoniacal Reference number IS0 25475:2016(E) ISO @IS02016 IS0 25475:2016(E) COPYRIGHT PROTECTED DOCUMENT IS0 2016, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form writtenpermission.Permission canberequestedfromeitherIsOattheaddressbelow orIso'smemberbodyinthecountryof the requester. ISO copyrightoffice Ch. de Blandonnet 8 · CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 [email protected] www.iso.org ii @ IS0 2016 - All rights reserved IS0 25475:2016(E) Contents Page Foreword ..iv 1 Scope .1 2 Normative references ..1 3 Terms and definitions 4 Principle 5 Reagents. ..1 6 Apparatus ..2 7 Sampling and sample preparation ..7 8 Procedure .7 8.1 Preparation of the solution 8.2 Analysis of the solution. .7 8.3 Blank. .9 8.4 Control test .9 9 Calculation and expression of the result ..9 10 .9 Precision 10.1 Inter-laboratory test. ..9 10.2 Repeatability .9 10.3 Reproducibility .10 11 Test report ..10 Annex A (informative) Results of the inter-laboratory tests ..11 Bibliography ..12 @ IS0 2016 - All rights reserved iii