DIN EN ISO 27107-2010 Animal and vegetable fats and oils - Determination of peroxide value - Potentiometric end-point determination (ISO 27107 2008 corrected version 2009-05-15) Ge.pdf

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1、August 2010 Translation by DIN-Sprachendienst.English price group 11No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS

2、 67.200.10!$j6Y“1711954www.din.deDDIN EN ISO 27107Animal and vegetable fats and oils Determination of peroxide value Potentiometric end-point determination (ISO 27107:2008, correctedversion 2009-05-15)English translation of DIN EN ISO 27107:2010-08Tierische und pflanzliche Fette und le Bestimmung de

3、r Peroxidzahl Potentiometrische Endpunktbestimmung (ISO 27107:2008, korrigierte Fassung2009-05-15)Englische bersetzung von DIN EN ISO 27107:2010-08Corps gras dorigines animale et vgtale Dtermination de lindice de peroxyde Dtermination avec point darrt potentiomtrique (ISO 27107:2008, version corige2

4、009-05-15)Traduction anglaise de DIN EN ISO 27107:2010-08SupersedesDIN EN ISO 27107:2009-02www.beuth.deIn case of doubt, the German-language original shall be considered authoritative.Document comprises 18 pages07.10 DIN EN ISO 27107:2010-08 2 A comma is used as the decimal marker. National foreword

5、 This standard has been prepared by Technical Committee ISO/TC 34 “Food products” (Secretariat: AFNOR, France) in collaboration with Technical Committee CEN/TC 307 “Oilseeds, vegetable and animal fats and oils and their by-products Methods of sampling and analysis” (Secretariat: AFNOR, France). The

6、responsible German bodies involved in its preparation was the Normenausschuss Lebensmittel und landwirtschaftliche Produkte (Food and Agricultural Products Standards Committee), Working Committee NA 057-05-05 AA Gemeinschaftsausschuss fr die Analytik von Fetten, len, Fettprodukten, verwandten Stoffe

7、n und Rohstoffen. The DIN Standards corresponding to the International Standards referred to in this document are as follows: ISO 661 DIN EN ISO 661 ISO 3960 DIN EN ISO 3960 ISO 5555 DIN EN ISO 5555 ISO 5725-1 DIN ISO 5725-1 ISO 5725-2 DIN ISO 5725-2 Amendments This standard differs from DIN EN ISO

8、27107:2009-02 as follows: a) Introduction, lines 9 and 10, “greater than” and “less than or equal to”, replace “” and “”, respectively. b) Introduction, line 11, “0 mmol to 15 mmol” has become “0 meq to 30 meq”. c) Subclause 5.6, final sentence, has been reedited to correct details of blue colour fo

9、rmation. d) Subclause 6.5 now contains a readability figure of 0,000 1 g, not 0,001 g. e) Subclause 9.2.2, line 1, now refers to 0,001 g instead of 0,001 mg. f) Subclause 9.2.2, paragraph 4, now contains a reedited calculation of the factor, using symbol F rather than f. g) The heading “10.1 Calcula

10、tion” has been deleted. h) Clause 10, paragraph 1, has been revised to incorporate factor, F, from the revised subclause 9.2.2. i) In Figure A.1, “PV =” has become “PV:” (five times). Previous editions DIN EN ISO 27107: 2009-02 DIN EN ISO 27107:2010-08 3 National Annex NA (informative) Bibliography

11、DIN EN ISO 661, Animal and vegetable fats and oils Preparation of test sample DIN EN ISO 3960, Animal and vegetable fats and oils Determination of peroxide value Iodometric (visual) endpoint determination DIN EN ISO 5555, Animal and vegetable fats and oils Sampling DIN ISO 5725-1, Accuracy (trueness

12、 and precision) of measurement methods and results Part 1: General principles and definitions DIN ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method DIN EN I

13、SO 27107:2010-08 4 This page is intentionally blank EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 27107 April 2010 ICS 67.200.10 Supersedes EN ISO 27107:2008English Version Animal and vegetable fats and oils - Determination of peroxide value - Potentiometric end-point determination (ISO 2

14、7107:2008, corrected version 2009-05-15 ) Corps gras dorigines animale et vgtale - Dtermination de lindice de peroxyde - Dtermination avec point darrt potentiomtrique (ISO 27107:2008, version corrige 2009-05-15) Tierische und pflanzliche Fette und le - Bestimmung der Peroxidzahl - Potentiometrische

15、Endpunktbestimmung (ISO 27107:2008, korrigierte Fassung 2009-05-15) This European Standard was approved by CEN on 13 March 2010. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standar

16、d without any alteration. Up-to-date lists and bibliographical references concerning such national standards 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 la

17、nguage made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Est

18、onia, Finland, France, Germany, 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 STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUR

19、OPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 27107:2010: EContents Page Foreword3 Introduction .4 1 Scope 5 2 Normative references 5 3 Ter

20、ms and definitions .5 4 Principle5 5 Reagents.6 6 Apparatus .7 7 Sampling.7 8 Preparation of the test sample .7 9 Procedure .8 10 Calculation and expression of results.9 11 Precision.10 12 Test report 10 Annex A (informative) Examples of potentiometric titration curves11 Annex B (informative) Result

21、s of an interlaboratory test12 Bibliography 14 DIN EN ISO 27107:2010-08 EN ISO 27107:2010 (E) 2 Foreword The text of ISO 27107:2008, corrected version 2009-05-15 has been prepared by Technical Committee ISO/TC 34 “Food products” of the International Organization for Standardization (ISO) and has bee

22、n taken over as EN ISO 27107:2010 by Technical Committee CEN/TC 307 “Oilseeds, vegetable and animal fats and 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 October 2010, and conflicting national

23、standards shall be withdrawn at the latest by October 2010. 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. This document supersedes E

24、N ISO 27107:2008. 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, Estonia, Finland, France, Germany, Greece, Hungary

25、, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice EN ISO 27107:2010 without any modification. The text of ISO 27107:2008, corrected version 2009-05

26、-15 has been approved by CEN as a DIN EN ISO 27107:2010-08 EN ISO 27107:2010 (E) 3 oils and their by-products Methods of sampling and analysis” the secretariat of which is held by AFNOR. Introduction Over many years, various methods have been developed for the determination of peroxides in fats and

27、oils. Their general principle is the liberation of iodine from potassium iodide in an acid medium. The method according to Wheeler (Reference 6) was first adopted in standards more than 50 years ago by different bodies, and is widely used to control commodities by producers, receivers, and official

28、laboratories. In national and international food legislation (including Codex Alimentarius), acceptable limits for peroxide values are often specified. Due to anomalies in the reproducibility of the results, it was noticed that there are slight differences between the standardized methods. A very im

29、portant point is the dependence of the result on the amount of sample used for the determination. As the determination of the peroxide value (PV) is a highly empirical procedure, ISO/TC 34/SC 11 has decided to fix the sample mass at 5 g for PV greater than 1, and at 10 g for PV less than or equal to

30、 1, and to limit the applicability of this method to animal and vegetable fats and oils with peroxide values from 0 meq to 30 meq of active oxygen per kilogram. The users of this International Standard should be aware that the results obtained can be slightly lower than with previous standards. DIN

31、EN ISO 27107:2010-08 EN ISO 27107:2010 (E) 4 1 Scope This International Standard specifies a method for the potentiometric end-point determination of the peroxide value, in milliequivalents of active oxygen per kilogram, of animal and vegetable fats and oils. The method is applicable to all animal a

32、nd vegetable fats and oils, fatty acids and their mixtures with peroxide values from 0 meq to 30 meq of active oxygen per kilogram. It is also applicable to margarines and fat spreads with varying water content. The method is not applicable to milk fats or lecithins. NOTE A method for the iodometric

33、 (visual) determination of the peroxide value is given in ISO 3960. For milk fats, a method is specified in ISO 3976. 2 Normative references The following referenced documents are indispensable for the application of this document. For undated references, the latest edition of the referenced documen

34、t (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 peroxide value PV quantity of those substances in the sample, expressed in terms of a

35、ctive oxygen, that oxidize potassium iodide under the conditions specified in this International Standard NOTE The peroxide value is usually expressed in milliequivalents of active oxygen per kilogram of oil, but it may also be expressed (in SI units) as millimoles of active oxygen per kilogram of o

36、il. The value expressed in millimoles of active oxygen per kilogram is half that expressed in milliequivalents of active oxygen per kilogram. Multiplication of the peroxide value (milliequivalents of active oxygen per kilogram) by the equivalent mass of oxygen (equalling 8) gives the active oxygen m

37、ass fraction in milligrams per kilogram of oil. 4 Principle The sample is dissolved in isooctane and glacial acetic acid, and potassium iodide is added. The iodide liberated by the peroxides is determined volumetrically with a sodium thiosulfate standard solution. The end-point of the titration is d

38、etermined electrochemically. DIN EN ISO 27107:2010-08 EN ISO 27107:2010 (E) 5 5 Reagents WARNING Attention is drawn to national regulations that specify the handling of hazardous substances, and users obligations thereunder. Technical, organizational and personal safety measures shall be followed. U

39、nless otherwise specified, use only reagents of recognized analytical grade. All reagents shall be free of dissolved oxygen. 5.1 Water, distilled, boiled, and cooled to 20 C. 5.2 Glacial acetic acid, mass fraction 100 %, degassed in an ultrasonic bath under vacuum or by purging with a stream of pure

40、 and dry inert gas (carbon dioxide or nitrogen). 5.3 Isooctane (2,2,4-trimethylpentane), degassed in an ultrasonic bath under vacuum or by purging with a stream of pure and dry inert gas (carbon dioxide or nitrogen). 5.4 Glacial acetic acid/isooctane solution, prepared by mixing 60 ml glacial acetic

41、 acid (5.2) and 40 ml isooctane (5.3). Volume fraction of glacial acetic acid: = 60 ml/100 ml; volume fraction of isooctane: = 40 ml/100 ml. The mixture is degassed in an ultrasonic bath under vacuum or by purging with a stream of pure and dry inert gas (carbon dioxide or nitrogen). 5.5 Potassium io

42、dide, free from iodine and iodates. 5.6 Saturated potassium iodide solution, mass concentration (KI) = 175 g/100 ml. Dissolve approximately 14 g potassium iodide in approximately 8 g freshly boiled water (5.1) at room temperature. Make sure the solution remains saturated (i.e. some undissolved cryst

43、als remain in the container). Store in the dark and prepare freshly every day. Test the solution as follows: add two drops of starch solution to 0,5 ml of the potassium iodide solution in 30 ml of the glacial acetic acid/isooctane solution (5.4). If a blue colour is formed and if more than one drop

44、of sodium thiosulfate standard solution (5.7) is needed to remove it, discard the potassium iodide solution. 5.7 0,1 N sodium thiosulfate standard solution, amount of substance concentration c(Na2S2O3) = 0,1 mol/l. Use only freshly boiled water (5.1) for the preparation of this solution, possibly pu

45、rged with nitrogen. This solution can be used for 1 month and shall be stored in an amber-stained bottle. 5.8 0,01 N sodium thiosulfate standard solution, amount of substance concentration c(Na2S2O3) = 0,01 mol/l. Pipette (6.3) 100 ml of the 0,1 N sodium thiosulfate standard solution (5.7) into a vo

46、lumetric flask of capacity 1 000 ml (6.9). Make up to the mark with water (5.1). After homogenization, transfer the obtained 0,01 N sodium thiosulfate standard solution to an amber-stained bottle. Prepare the 0,01 N sodium thiosulfate standard solution freshly from the 0,1 N sodium thiosulfate stand

47、ard solution just before use or determine the titre daily. As experience shows, the stability is limited and depends upon the pH value and the content of free carbon dioxide. Use only freshly boiled water (5.1) for the dilution, possibly purged with nitrogen. 5.9 Potassium iodate(V) volumetric stand

48、ard, secondary reference material, traceable to the National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA. 5.10 Hydrochloric acid, amount of substance concentration c(HCl) = 4 mol/l. DIN EN ISO 27107:2010-08 EN ISO 27107:2010 (E) 6 6 Apparatus Usual laboratory apparatus and, i

49、n particular, the following. 6.1 Automatic titrator with processor, dosing device, stirrer and electrodes. If other apparatus is used, the procedure shall be optimized for the relevant apparatus. The apparatus shall be able to perform a dynamic titration (fast at the beginning, slow near the end-point). This is necessary to minimize the titration time whilst achieving a slow titration near the end-point. 6.2 Combined platinum electrode. 6.3 Pipettes, of capacities 0,5 ml, 1 ml, 10 ml and 100 ml. Suitable automatic pi