1、BS EN ISO 8534:2017Animal and vegetable fats andoils Determination of watercontent Karl Fischer method(pyridine free) (ISO 8534:2017)BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS EN ISO 8534:2017 BRITISH STANDARDNational forewordThis British Standard is the UK i
2、mplementation of EN ISO 8534:2017. It supersedes BS EN ISO 8534:2008 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee AW/307, Oilseeds, animal and vegetable fats and oils andtheir by-products.A list of organizations represented on this committee can beob
3、tained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2017. Published by BSI Standards Limited 2017ISBN 978 0 580 94410 9ICS 67.200.10Compliance wi
4、th a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 28 February 2017.Amendments/Corrigenda issued since publicationDate Text affectedEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NO
5、RM EN ISO 8534 February 2017 ICS 67.200.10 Supersedes EN ISO 8534:2008English Version Animal and vegetable fats and oils - Determination of water content - Karl Fischer method (pyridine free) (ISO 8534:2017) Corps gras dorigines animale et vgtale - Dtermination de la teneur en eau - Mthode de Karl F
6、ischer (sans pyridine) (ISO 8534:2017) Tierische und pflanzliche Fette und le - Bestimmung des Wassergehalts - Karl-Fischer-Verfahren (pyridinfrei) (ISO 8534:2017) This European Standard was approved by CEN on 8 February 2017. CEN members are bound to comply with the CEN/CENELEC Internal Regulations
7、 which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. Thi
8、s European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN memb
9、ers are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portug
10、al, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2017 CEN All rights of exploitation in
11、 any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 8534:2017 EBS EN ISO 8534:2017EN ISO 8534:2017 (E) 3 European foreword This document (EN ISO 8534:2017) has been prepared by Technical Committee ISO/TC 34 “Food products” in collaboration with Technical Committee
12、 CEN/TC 307 “Oilseeds, vegetable and animal fats and oils and their by-products - Methods of sampling and analysis” the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the
13、 latest by August 2017, and conflicting national standards shall be withdrawn at the latest by August 2017. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or al
14、l such patent rights. This document supersedes EN ISO 8534:2008. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Est
15、onia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement no
16、tice The text of ISO 8534:2017 has been approved by CEN as EN ISO 8534:2017 without any modification. BS EN ISO 8534:2017ISO 8534:2017(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Principle 15 Reagents 16 Apparatus . 27 Sampling 28 Preparation of the tes
17、t sample . 29 Procedure. 39.1 Titre 39.2 Test portion 49.3 Determination . 510 Expression of results 511 Precision of the method 611.1 Interlaboratory test. 611.2 Repeatability . 611.3 Reproducibility . 612 Test report . 6Annex A (informative) Results of interlaboratory tests 7Annex B (informative)
18、Information and precision data on the use of the coulometric method 8Bibliography .10 ISO 2017 All rights reserved iiiContents PageBS EN ISO 8534:2017ISO 8534:2017(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bo
19、dies). The work of preparing International Standards is normally carried out through ISO 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 an
20、d non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are de
21、scribed in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www. iso. org/ directives).Attention is dr
22、awn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/oron
23、the ISO list of patent declarations received (see www. iso. org/ patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assess
24、ment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in theTechnical Barriers to Trade (TBT) see the following URL: www .iso. org/iso/ foreword. html.This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 11, Animal a
25、nd vegetable fats and oils.This third edition cancels and replaces the second edition (ISO 8534:2008), of which it constitutes a minor revision to exclude the applicability for fat coming from milk and milk products.iv ISO 2017 All rights reservedBS EN ISO 8534:2017ISO 8534:2017(E)IntroductionThe de
26、termination of the water content of fats and oils according to Karl Fischer is carried out by two different procedures. This document specifies the volumetric Karl Fischer method for the determination of higher milligram levels of water (high level moisture). It is used for samples having between 1
27、mg and 100 mg of water in the sample.Annex B specifies a coulometric titration, which requires between 10 g and 10 mg water in the sample. The coulometric method is more sensitive than the volumetric method and permits the determination of lower water contents. ISO 2017 All rights reserved vBS EN IS
28、O 8534:2017ISO 8534:2017(E) BS EN ISO 8534:2017Animal and vegetable fats and oils Determination of water content Karl Fischer method (pyridine free)1 ScopeThis document specifies a method for the determination of the water content of animal and vegetable fats and oils (hereinafter referred to as fat
29、s) using Karl Fischer apparatus and a reagent which is free of pyridine.Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this document.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of their co
30、ntent constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 661, Animal and vegetable fats and oils Preparation of test sample3 Terms and definition
31、sFor the purposes of this document, the following terms and definitions apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p :/ w
32、ww .iso .org/ obp3.1water contentmass, in grams per 100 g of sample, of water as determined in accordance with the method specified in this documentNote 1 to entry: The water content is expressed as a percentage mass fraction.4 PrincipleDissolved fat is titrated against an iodine solution and sulfur
33、 dioxide (SO2) is oxidized by iodine in the presence of water. In principle, the chemical reaction in Formula (1) takes place:HO ISOCHOHRNRNH SO CH RNHI22 23 4332+ +(1)The alcohol reacts with SO2and a nitrogenous base (RN) to form an intermediate alkylsulfite salt, which is then oxidized by iodine t
34、o an alkylsulfate salt. This oxidation reaction consumes water contained in the sample. The end point is monitored potentiometrically.5 ReagentsWARNING Comply with any local regulations which specify the handling of hazardous substances. Technical, organizational and personal safety measures shall b
35、e followed.INTERNATIONAL STANDARD ISO 8534:2017(E) ISO 2017 All rights reserved 1BS EN ISO 8534:2017ISO 8534:2017(E)It is recommended that “ready for use” working solvents be used, either one-component reagents (5.1.1) or two-component reagents (5.1.2). Reagents with a titre of 1 mg and 2 mg water p
36、er millilitre are required for acceptable performance.5.1 Karl Fischer reagents, consist of one-component reagents or two-component reagents for volumetric determination.5.1.1 One-component reagents, contain all the reactant in the titrant solution: iodine, sulfur dioxide, and imidazole, dissolved i
37、n a suitable alcohol. Methanol is typically used as the working medium in the titration cell.Absolute methanol is the solvent of choice. But for fats and oils, use a mixture of absolute methanol and absolute chloroform (the methanol content should be at least 25 % volume fraction, or optimally 50 %
38、volume fraction).5.1.2 Two-component reagents, consist of all necessary reactants for the titration, but in two different solutions. The titrating agent (usually known as the titrant) contains only iodine and methanol, while the solvent containing the other Karl Fischer reaction components is used a
39、s the working medium in the titration cell.5.2 Water standard, commercially prepared standard with a certified concentration of 10 mg/g (1,0 % mass fraction).6 ApparatusUsual laboratory apparatus and, in particular the following.6.1 Karl Fischer apparatus, set up according to the manufacturers recom
40、mendations for the determination of water in fats and oils. Set up and conduct protocols for routine maintenance as recommended by the manufacturer. Use an airtight vessel and do not place the instrument in high humidity areas. Do not place instruments or handle samples near water sources, such as t
41、aps, sinks, and dishwashers in the laboratory.6.2 Analytical balance, readable to the nearest 0,1 mg.6.3 Syringes, of capacity 1 ml, 2 ml, 5 ml, 10 ml, and 20 ml.To ensure accurate and reproducible results from the water standard, use a glass gastight syringe. For water standard 10,0, use a 10 ml sy
42、ringe and for either the water standard 1,00 or 0,10, use a 5 ml syringe. In addition to the appropriate size syringe, use a needle that is long enough to allow for a subsurface injection when injecting through the instruments septum.7 SamplingA representative sample should have been sent to the lab
43、oratory. It should not have been damaged or changed during transport or storage.Sampling is not part of the method specified in this document. A recommended sampling method is given in ISO 5555.8 Preparation of the test samplePrepare the test sample in accordance with ISO 661.2 ISO 2017 All rights r
44、eservedBS EN ISO 8534:2017ISO 8534:2017(E)The determination of water is conducted by adjusting the sample size to have between 1 mg and 100 mg water for the volumetric titration (the main body of this document) and between 10 g and 10 mg for the coulometric titration (Annex B) using Karl Fischer ins
45、truments and reagents which have been validated with standard water solutions over the necessary range. For the volumetric determination, a minimum amount of 0,5 ml Karl Fischer reagent shall be used for the titration.9 Procedure9.1 Titre9.1.1 The titre shall be determined daily for each bottle of t
46、itrant.9.1.2 Prepare the instrument according to the manufacturers recommendations for calibration.9.1.3 Add 20 ml to 40 ml of working solvent (5.1) to the titration vessel. The solvent should cover the platinum electrodes.9.1.4 Titrate the vessel to a stable dry end point.CAUTION Take care not to o
47、vertitrate.9.1.5 Determine the titre of the titrant using the water standard (5.2) and a syringe (6.3). Sample mass is determined by difference.9.1.5.1 Weigh, to the nearest 0,1 mg, approximately 1 g of the water standard into a syringe, placed on the analytical balance (6.2).Upon opening the ampoul
48、e, withdraw a small portion of the standard to rinse the syringe; 1 ml to 2 ml is sufficient. Rinse the entire interior of the syringe and discard the rinsings. Then, immediately transfer the remaining standard to the syringe and expel any air bubbles. Using mass by difference make at least three in
49、jections from the syringe.9.1.5.2 When the mass displayed is stable, tare the balance.9.1.5.3 Inject the water sample into the titration vessel and close the vessel.9.1.5.4 Place the syringe back on the balance. Record the mass of the water injected to the nearest 0,1 mg. The mass will be displayed as a negative value.9.1.5.5 Enter the sample mass in the instrument.9.1.6 Start the titration and record the titre when a stable end point is reached. Some instruments may require calculation of titre from the displayed percentage
