ISO INTERNATIONAL STANDARD 19563 First edition 2017-01 Determination of theanine in tea and instant tea in solid form using high- performance liquid chromatography Détermination de la théanine dans le thé et le the instantané sous forme solide en utilisant la chromatographie en phase liquide a haute performance Reference number IS0 19563:2017(E) International Organization for Standardization @ IS0 2017 ee=ZHEJIANG INST OF STANDARDIZATION C1 5956617 mitted without license from IHS IS0 19563:2017(E) COPYRIGHT PROTECTED DOCUMENT 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. ISO copyright office 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 Internationai ibrg Drganization for Standardization Licensee-ZHEJIANG INST OF STANDARDIZzRoISQ7 - All rights reserved networking permited without license from IHS IS0 19563:2017(E) Contents Page Foreword ..iv Introduction. ..V 1 Scope. ..1 2 Normative references 3 Terms and definitions 4 Principle ..1 5 Reagents. ..2 6 Apparatus ..3 7 Sampling. ..3 8 Preparation of test samples ..3 9 Procedure. .3 9.1 General .3 9.2 Determination of dry matter content. 4 9.3 Test portion .4 9.3.1 Sample preparations. 4 9.3.2 Sample clean-up (using a polyamide column) - Optional. .4 9.4 Determination. .5 9.4.1 Adjustment of the apparatus. 5 9.4.2 HPLC analysis .5 9.4.3 Identification ..5 10 Calculation .6 11 Precision .6 11.1 Interlaboratory test ..6 11.2 Repeatability .6 11.3 Reproducibility 12 Test report Annex A (informative) Typical theanine calibration graph .8 Annex B (informative) Typical chromatograms. ..9 Annex C (informative) Results of interlaboratory tests .12 Bibliography ..13 iii icensee=ZHEJIANG INST OF STANDARDIZATION C1 5956617 without license from IHS