ISO INTERNATIONAL STANDARD 17319 First edition 2015-05-15 Fertilizers and soil conditioners Determination of water-soluble potassium content Potassium tetraphenylborate gravimetric method Matieres fertilisantes -Dosage de la teneur en potassium - Méthode gravimétrique au tétraphénylborate de potassium Reference number IS017319:2015(E) ISO International Organization for Standardization e=Zhejang Institute of Standardization 5956617 @IS02015 HS unde Not for Resale, 2015/8/7 05:23:03 mitted without license from IHS IS0 17319:2015(E) COPYRIGHT PROTECTED DOCUMENT IS0 2015, 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 [email protected] www.iso.org Internationai ibr DrganizationforStandardization Not for Resale, 2015/8/7 05:23:03 networking permited withoutlicense from IHS IS0 17319:2015(E) Contents Page Foreword ..iv 1 Scope .1 2 Normative references ..1 3 Principle. 4 Reagents 5 Apparatus and materials ..2 6 Test solution .2 7 Procedure. .2 7.1 Aliquot portion of test solution .2 7.1.1 Procedure in the presence of cyanamide and/or organic materials .2 7.1.2 Procedure in the absence of cyanamide and/or organic materials 3 7.2 Determination. .3 7.3 Blank test 3 7.4 Periodic quality control .3 8 Expression of results. .3 8.1 Calculation .3 8.2 Precision. ..4 8.2.1 Ring test .4 8.2.2 Repeatability, r ..4 8.2.3 Reproducibility, R ..4 9 Test report .4 Annex A (informative) Report of Method Accuracy ..5 Annex B (informative) Interlaboratory testing ..13 Bibliography .19 ii icensee=Zhejiang Institute of Standardization 5956617 ithout license from IHS