ISO INTERNATIONAL STANDARD 13904 Second edition 2016-02-15 Animal feeding stuffs Determination of tryptophan content Aliments des animaux - Dosage du tryptophane Reference number ISO 13904:2016(E) ISO International Organization for Standardization See=ZHEJIANG INST OF STANDARDIZATION C1 5956617 @IS02016 vided by IHS under I Not for Resale, 2016/4/26 02:00:18 No reproduction or networking permitted without license from IHS IS0 13904:2016(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 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 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 Licensee-ZHEJIANG INST OF STANDARDIZAISQ 0d6 - All rights reserved networking permited without license from IHS IS0 13904:2016(E) Contents Page Foreword ..iv 1 Scope. .1 2 Principle ..1 3 Reagents and materials 4 Apparatus ..3 5 Procedure ..4 5.1 Preparation of samples 4 5.1.1 Feeding stuffs ..4 5.1.2 Commercial pure substances and premixtures containing more than 2 % of tryptophan. .4 5.2 Determination of free tryptophan (extract) 4 5.2.1 Feedingstuffs 4 5.2.2 Commercial pure substances and premixtures containing more than 2 % oftryptophan .4 5.3 Determination of total tryptophan (hydrolysates) .5 5.4 HPLC determination. .5 6 Calculation of results .6 6.1 Feedingstuffs 6 6.2 Commercial pure products and premixtures containing more than 2 % of tryptophan... .6 6.2.1 Control of the calibration. .6 6.2.2 Calculation .6 7 Precision .7 7.1 Interlaboratory test 7 7.1.1 Feeding stuffs 7 7.1.2 Commercial pure substances and premixtures containing more than 2 % of tryptophan 7 7.2 Repeatability 7 7.2.1 Feedingstuffs 7.2.2 Commercial pure substances and premixtures containing more than 2 % oftryptophan 7 7.3 Reproducibility 7 7.3.1 Feeding stuffs. 7 7.3.2 Pure products and premixtures containing more than 2 % of tryptophan ..8 8 Test report .8 Annex A (informative) Results of an interlaboratory test .9 Annex B (informative) Observations on the method ..11 Annex C (informative) Sample preparation: Example for analyses in pure products andpremixtures ..12 Annex D (informative) Results of an interlaboratory test for tryptophan in pure products and premixtures containing more than 2 % of tryptophan .13 Bibliography .14 ii censee=ZHEJIANG INST OF STANDARDIZATION C1 5956617 thout license from IHS