EN ISO 8534-2008 459 Animal and vegetable fats and oils - Determination of water content - Karl Fischer method (pyridine free) (ISO 8534 2008)《动物和植物的脂肪和油 水分的测定 卡尔·费休法(无吡啶)》.pdf

1、BS EN ISO8534:2008ICS 67.200.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDAnimal and vegetablefats and oils Determination of watercontent Karl Fischermethod (pyridine free)(ISO 8534:2008)Copyright European Committee for Standardization Provided by IHS under

2、 license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-This British Standard was published under theauthority of the StandardsPolicy and StrategyCommittee on 30 BSI 2008ISBN 978 0 580 58780 1Amendments/corrigenda issued since publicationDate CommentsBS EN

3、 ISO 8534:2008National forewordThis British Standard is the UK implementation of EN ISO 8534:2008. Itsupersedes BS 684-2.1:1996 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee AW/307, Oil seeds, animal and vegetable fats and oils andtheir by products.A

4、list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal

5、 obligations.September 2008Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 8534July 2008ICS 67.200.10English VersionAnimal a

6、nd vegetable fats and oils - Determination of watercontent - Karl Fischer method (pyridine free) (ISO 8534:2008)Corps gras dorigines animale et vgtale - Dterminationde la teneur en eau - Mthode de Karl Fischer (sanspyridine) (ISO 8534:2008)Tierische und pflanzliche Fette und le - Bestimmung desWasse

7、rgehalts - Karl-Fischer-Verfahren (pyridinfrei) (ISO8534:2008)This European Standard was approved by CEN on 4 June 2008.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without

8、any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made

9、by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Ge

10、rmany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGMa

11、nagement Centre: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN ISO 8534:2008: ECopyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reprodu

12、ction or networking permitted without license from IHS-,-,-BS EN ISO 8534:2008EN ISO 8534:2008 (E) 3 Foreword This document (EN ISO 8534:2008) has been prepared by Technical Committee ISO/TC 34 “Agricultural food products“ in collaboration with Technical Committee CEN/TC 307 “Oilseeds, vegetable and

13、 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 latest by January 2009, and conflic

14、ting national standards shall be withdrawn at the latest by January 2009. 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 all such patent rights. According to

15、 the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lith

16、uania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 8534:2008 has been approved by CEN as a EN ISO 8534:2008 without any modification. Copyright European Committee for Stan

17、dardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN ISO 8534:2008ISO 8534:2008(E) ISO 2008 All rights reserved iiiForeword ISO (the International Organization for Standardization) is a worldwide federation of nati

18、onal standards bodies (ISO member bodies). 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. Internat

19、ional organizations, governmental and 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. International Standards are drafted in accordance with the ru

20、les given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. 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

21、 least 75 % of the member bodies casting a vote. Attention is drawn 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. ISO 8534 was prepared by Technical Committee ISO/TC

22、34, Food products, Subcommittee SC 11, Animal and vegetable fats and oils. This second edition cancels and replaces the first edition (ISO 8534:1996), which has been technically revised. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduct

23、ion or networking permitted without license from IHS-,-,-BS EN ISO 8534:2008ISO 8534:2008(E) iv ISO 2008 All rights reservedIntroduction The determination of the water content of fats and oils according to Karl Fischer is carried out by two different procedures. This International Standard specifies

24、 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 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

25、 coulometric method is more sensitive than the volumetric method and permits the determination of lower water contents. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN ISO

26、8534:2008INTERNATIONAL STANDARD ISO 8534:2008(E) ISO 2008 All rights reserved 1Animal and vegetable fats and oils Determination of water content Karl Fischer method (pyridine free) 1 Scope This International Standard specifies a method for the determination of the water content of animal and vegetab

27、le fats and oils (hereinafter referred to as fats) using Karl Fischer apparatus and a reagent which is free of pyridine. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated

28、 references, the latest edition of the referenced document (including any amendments) applies. ISO 661, Animal and vegetable fats and oils Preparation of test sample 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 water content mass, in grams

29、 per 100 g of sample, of water as determined in accordance with the method specified in this International Standard NOTE The water content is expressed as a percentage mass fraction. 4 Principle Dissolved fat is titrated against an iodine solution and sulfur dioxide (SO2) is oxidized by iodine in th

30、e presence of water. In principle, the chemical reaction in Equation (1) takes place: H2O + I2+ SO2+ CH3OH + 3RN RNHSO4CH3+ 2RNHI (1) The alcohol reacts with SO2and a nitrogenous base (RN) to form an intermediate alkylsulfite salt, which is then oxidized by iodine to an alkylsulfate salt. This oxida

31、tion reaction consumes water contained in the sample. The end point is monitored potentiometrically. 5 Reagents WARNING Comply with any local regulations which specify the handling of hazardous substances. Technical, organizational and personal safety measures shall be followed. It is recommended th

32、at “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 per millilitre are required for acceptable performance. Copyright European Committee for Standardization Provided by IHS under license wi

33、th CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN ISO 8534:2008ISO 8534:2008(E) 2 ISO 2008 All rights reserved5.1 Karl Fischer reagents, consist of one-component reagents or two-component reagents for volumetric determination. 5.1.1 One-component reagents

34、, contain all the reactant in the titrant solution: iodine, sulfur dioxide, and imidazole, dissolved in 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 an

35、d absolute chloroform (the methanol content should be at least 25 % volume fraction, or optimally 50 % 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 onl

36、y iodine and methanol, while the solvent containing the other Karl Fischer reaction components is used as 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 Apparatus Usual laboratory apparat

37、us and, in particular the following. 6.1 Karl Fischer apparatus, set up according to the manufacturers recommendations 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

38、 instrument in high humidity areas. Do not place instruments or handle samples near water sources such as taps, 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 repro

39、ducible results from the water standard, use a glass gastight syringe. For water standard 10,0, use a 10 ml syringe, 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 w

40、hen injecting through the instruments septum. 7 Sampling A representative sample should have been sent to the laboratory. It should not have been damaged or changed during transport or storage. Sampling is not part of the method specified in this International Standard. A recommended sampling method

41、 is given in ISO 5555. 8 Preparation of the test sample Prepare the test sample in accordance with ISO 661. 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 International Standard) and betwe

42、en 10 g and 10 mg for the coulometric titration (Annex B) using Karl Fischer instruments 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. C

43、opyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN ISO 8534:2008ISO 8534:2008(E) ISO 2008 All rights reserved 39 Procedure 9.1 Titre The titre shall be determined daily for eac

44、h bottle of titrant. 9.1.1 Prepare the instrument according to the manufacturers recommendations for calibration. 9.1.2 Add 20 ml to 40 ml of working solvent (5.1) to the titration vessel. The solvent should cover the platinum electrodes. 9.1.3 Titrate the vessel to a stable dry endpoint. CAUTION Ta

45、ke care not to overtitrate. 9.1.4 Determine the titre of the titrant using the water standard (5.2) and a syringe (6.3). Sample mass is determined by difference. 9.1.4.1 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

46、 opening the ampoule, 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

47、at least three injections from the syringe. 9.1.4.2 When the mass displayed is stable, tare the balance. 9.1.4.3 Inject the water sample into the titration vessel and close the vessel. 9.1.4.4 Place the syringe back on the balance. Record the mass of the water injected to the nearest 0,1 mg. The mas

48、s will be displayed as a negative value. 9.1.4.5 Enter the sample mass in the instrument. 9.1.5 Start the titration and record the titre when a stable endpoint is reached. Some instruments may require calculation of titre from the displayed percentage of water. 9.1.6 Average a minimum of three titre

49、 determinations. Record the arithmetic average. 9.1.7 Update the instrument titre value with the new setting. The titre, titrant, in milligrams per millilitre, can be calculated from Equation (2): 2sHO,stitranttitrantmwV = (2) where msis the mass, in grams, of the water standard; wH2O,sis the water con