ISO INTERNATIONAL STANDARD 19746 First edition 2017-02 Determination of urea content in urea- based fertilizers by high performance liquid chromatography (HPLC) Détermination de la teneur en urée dans les engrais a base d'urée par chromatographie liquide a haute performance (CLHP) Reference number IS0 19746:2017(E) International Organization for Standardization @ IS0 2017 ZHEJIANG INSTOFSTANDARDIZATION C15956617 ted without license from IHS IS0 19746:2017(E) COPYRIGHTPROTECTEDDOCUMENT IS0 2017, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form written permission. Permission can be requested from either ISO at the address below or ISO's member body in the country of the requester. ISOcopyrightoffice Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org Intenationaibr PrganizationforStandardization ensee-ZHEJIANG INST OF STANDARDIZRoISQ $17 - All rights reserved Not for Resale, 2017/5/11 02:19:24 etworking permitted without license from IHS IS0 19746:2017(E) Contents Page Foreword ..iv Introduction. ..V 1 Scope. ..1 2 Normative references 3 Terms and definitions ..1 4 Principles .1 5 Reagents. 6 Apparatus. ..2 7 Procedures .2 7.1 Preparation of test sample. .2 7.2 Preparation of the test solution .2 7.3 Preparation of urea working standard solution 3 7.4 HPLC conditions. .3 7.5 Preparation of standard curve. .3 7.6 Determination of the urea content in the test solution ..4 7.7 Calculation and expression of results 4 7.8 Precision.. .4 7.8.1 Repeatability, r 4 7.8.2 Reproducibility, R ..4 7.9 Test report. .4 Annex A (informative) Examples of the retention times of triuret, biuret, urea and some otherureaforms .5 Bibliography 8 iii e=ZHEJIANG INSTOFSTANDARDIZATION C15956617 vided by IHS under I vithoutlicense from IHS