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1 Nederlandse NEN-ISO 8534 Plantaardige en dierlijke oliën en vetten. Bepaling van het watergehalte. Methode volgens Karl Fischer (ISO 8543:1996) Animal and vegetable fats and oils. Determination of water content. Karl Fischer method (ISO 8543:1996) 1e druk, september 1996 ICS Als Nederlandse norm is aanvaard de internationale norm ISO 8534, 1 e druk, Dit document mag slechts op een stand-alone PC worden geinstalleerd. Gebruik op een netwerk is alleen. toestaan als een aanvullende licentieovereenkomst voor netwerkgebruik met NEN is afgesloten. This document may only be used on a stand-alone PC. Use in a network is only permitted when a supplementary license agreement for us in a network with NEN has been concluded. Normcommissie "Plantaardige en dierlijke oliën en vetten" Behoudens uitzondering door de wet gesteld mag zonder schriftelijke toestemming van het Nederlands Normalisatie-instituut niets uit deze uitgave worden verveelvoudigd en/of openbaar gemaakt door middel van fotokopie, microfilm, opslag in computerbestanden of anderszins, hetgeen ook van toepassing is op gehele of gedeeltelijke bewerking. Het Nederlands Normalisatie-instituut is met uitsluiting van ieder ander gerechtigd de door derden verschuldigde vergoedingen voor verveelvoudiging te innen en/of daartoe in en buiten rechte op te treden, voor zover deze bevoegdheid niet is overgedragen c.q. rechtens toekomt aan de Stichting Reprorecht. Hoewel bij deze uitgave de uiterste zorg is nagestreefd, kunnen fouten en onvolledigheden niet geheel worden uitgesloten. Het Nederlands Normalisatie-instituut en/of de leden van de commissies aanvaarden derhalve geen enkele aansprakelijkheid, ook niet voor directe of indirecte schade, ontstaan door of verband houdende met toepassing van door het Nederlands Normalisatie-instituut gepubliceerde uitgaven. Nederlands Normalisatie-instituut 1996 Nederlands Normalisatie-instituut Kalfjeslaan 2, Postbus 5059, 2600 GB Delft, Telefoon (015) , Fax (015)

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3 INTERNATIONAL STANDARD First edition Animal and vegetable fats and oils - Determination of water content - Karl Fischer method Corps gras d origines animale et v6g6 tale - D&ermination de la teneur en eau - M&hode de Karl Fischer Reference number IS0 8534:1996(E)

4 Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. IS0 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 IS was prepared by Technical Committee ISO/TC 34, Agricultural food products, Subcommittee SC 11, Animal and vegetable fats and oils. Annexes A to D of this International Standard are for information only. 0 IS 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. International Organization for Standardization Case Postale 56 l CH-1211 Geneve 20 l Switzerland Printed in Switzerland ii

5 INTERNATIONAL IS0 IS0 8534:1996(E) Animal and vegetable fats and oils - Determination of water content - Karl Fischer method WARNING - The chemicals pyridine, methanol, sulfur dioxide and chloroform are poisons. Therefore special care shall be taken during analysis and removal of the residues. Consult the restrictions for using these chemicals (poisons law, threshold limits for exposure of workers) in order to protect the environment and workers. 1 Scope 3 Definition This International Standard specifies a method using Karl Fischer reagent for the determination of the water content of animal and vegetable fats and oils (hereinafter referred to as fats) that do not contain impurities such as soaps or other alkaline compounds which may react to produce high results. It is only applicable to fats with low water content. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were 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 editions of the standards listed below. Members of IEC and IS0 maintain registers of currently valid International Standards. IS0 661: 1989, Animal and vegetable fats and oils - Preparation of test sample. IS0 3696: 1987, Water for analytical laboratory use - Specification and test methods. For the purposes of this International Standard, the following definition applies. 3.1 water content: Mass of water, as determined in accordance with the method specified in this International Standard, divided by the mass of the test portion. It is expressed as a percentage by mass. 4 Principle Addition of a test portion to a prepared mixture of solvent and reagent. Titration with Karl Fischer reagent and calculation of the water content. 5 Reagents Use only reagents of recognized analytical grade, and water complying with grade 2 in accordance with IS Anhydrous solvent: 2-methoxyethanol, propanl-01 or a specific solvent commercially prepared. 1

6 ISO8534:1996( IS0 5.2 Karl Fischer reagent, preferably commercially prepared. A non-pyridine reagent may be used if it has been shown to be suitable. 9.2 Test portion Weigh between 5 g and 20 g of the test sample to the nearest 0,Ol g. Determine the water equivalent of the reagent on each day on which it is used. See 9.4. NOTE 1 The preparation of Karl Fischer reagent containing pyridine is described in annex A. 9.3 Determination Add the test portion (9.2) to the reaction vessel and stir for 30 s to disperse it. Titrate with the Karl Fischer reagent to the same endpoint (9.1). 5.3 Disodium tartrate dihydrate, (Na2C,t-i~~6~2H20), crystalline. Record the amount of reagent used. Carry out a duplicate determination by adding a second test portion and repeating the titration. 6 Apparatus NOTE 2 If the test portion does not dissolve, another of Usual laboratory apparatus and, in particular, the following. the solvents (5.1) should be used, with the addition of chloroform if necessary. 6.1 Karl Fischer apparatus, fully automatic or semi-automatic, using an electrometric detection or visual determination of the endpoint. It is essential to use an airtight vessel which will prevent reaction with air humidity, and also to stir the contents of the reaction vessel efficiently. 7 Sampling It is important the laboratory receive a sample which is truly representative and has not been damaged or changed during transport or storage. Sampling is not part of the method specified in this International Standard. A recommended sampling method is given in IS Preparation of test sample Prepare the test sample in accordance with IS Procedure 9.1 Preparation of the reaction vessel Add solvent (5.1) to the reaction vessel of the Karl Fischer apparatus (6.1) until the electrode is immersed. Whilst stirring, add the Karl Fischer reagent (5.2) until the endpoint is reached, as indicated by the instrument reading or by a change in colour. Disregard the amount of reagent used. 9.4 Determination of the water equivalent of the reagent The water equivalent of the reagent shall be determined or checked by following the procedure specified in 9.2 and 9.3 using disodium tartrate dihydrate (5.3) or a known mass of water. 10 Expression of results The water content where W =-x100% VXP m is given by the equation W is the water content, expressed as a percentage by mass; V is the volume, in millilitres, of Karl Fischer reagent used; p is the water equivalent of the Karl Fischer reagent, in grams per millilitre; m is the mass, in grams, of the test portion. Take as the result the arithmetic mean of the two determinations provided that the requirements for repeatability (II.I) are met. 1) A suitable non-pyridine reagent is Hydranal-composite Z, containing iodine, sulfur dioxide and an amine dissolved in the solvent. Hydranal-composite 2 is supplied by Riedel-de Haen AG, SeePze/Hannover, 3016 Germany. This information is given for the convenience of users of this International Standard and does not constitute an endorsement by IS0 of this product. 2

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