ISO INTERNATIONAL STANDARD 2447 Second edition 1998-08-01 Fruit and vegetable products - Determination of tin content Produits dérivés des fruits et leégumes Détermination de la teneur enétain Reference number ISO 2447:1998(E) ISO 2447:1998(E) Foreword ISO(theInternationalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies(lSc member bodies). The work of preparing International Standards is normally carried out through IsO technical liaison with isO, also take part in the work. isO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 2447 was prepared by Technical Committee ISO/TC 34, Agricultural food products Subcommittee SC 3, Fruit and vegetable products. This second edition cancels and replaces the first edition (IsO 2447:1974), which has been technically revised ISO1998 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. InternationalOrganizationforStandardizatior Case postale 56. CH-1211 Geneve 20 · Switzerland Internet @iso.ch Printed in Switzerland INTERNATIONAL STANDARD@ISO ISO 2447:1998(E) Fruit and vegetable products Determination of tin content 1 Scope This International Standard specifies a method for the determination of the tin content in fruit and vegetable products. The method is applicable to products which may contain, per kilogram, up to: 1,25 g of copper; 0,6 g of lead; 6 g of zinc; 40 g of phosphorus. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISo maintain registers of currently valid International Standards. Iso 5515:1979, Fruits, vegetables and derived products — Decomposition of organic matter prior to analysis - Wet method. 3 Principle Afterdestructionof theorganicmatterbymeansof sulfuricandnitric acids,andconversionofthetintothestannic form, a complex is formed in a buffered solution of pH 1,o to pH 1,2 [the iron(IIl) being masked, if necessary, by reduction with ascorbic acidj. The complex is coloured orange with phenylfluorone and the colour compared with those obtained under the same conditions but starting from standard solutions of pure tin. 4 Reagents Use only reagents of recognized analytical grade, and distilled or demineralized water or water of equivalent purity. 4.1 Sulfuric acid, P20 = 1,84 g/ml. 4.2 Dilute sulfuric acid, 1,25 mol/l. 4.3 Ascorbic acid, 50 g/l solution. 4.4 Nitric acid, P20 = 1,42 g/ml.