1、BS EN ISO 6320:2017Animal and vegetable fatsand oils Determinationof refractive index (ISO6320:2017)BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS EN ISO 6320:2017 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN ISO 6320:2017
2、. It supersedes BS EN ISO 6320:2000 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee AW/307, Oilseeds, animal and vegetable fats and oils and their by-products.A list of organizations represented on this committee can be obtained on request to its secre
3、tary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017.Published by BSI Standards Limited 2017ISBN 978 0 580 94412 3 ICS 67.200.10Compliance with a British Standard cannot
4、 confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 March 2017.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 6320 Marc
5、h 2017 ICS 67.200.10 Supersedes EN ISO 6320:2000English Version Animal and vegetable fats and oils - Determination of refractive index (ISO 6320:2017) Corps gras dorigines animale et vgtale - Dtermination de lindice de rfraction (ISO 6320:2017) Tierische und pflanzliche Fette und le - Bestimmung des
6、 Brechungsindex (ISO 6320:2017) This European Standard was approved by CEN on 9 March 2017. 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 standard without any alteration. Up-to-date
7、lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC 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 by translation un
8、der 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 members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former
9、 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 United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION
10、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 any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 6320:2017 EBS EN ISO 6320:2017EN ISO 6320:2017
11、(E) 3 European foreword This document (EN ISO 6320:2017) has been prepared by Technical Committee ISO/TC 34 “Food products” in collaboration with Technical Committee CEN/TC 307 “Oilseeds, vegetable and animal fats and oils and their by-products - Methods of sampling and analysis” the secretariat of
12、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 September 2017, and conflicting national standards shall be withdrawn at the latest by September 2017. Attention is drawn to
13、 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 EN ISO 6320:2000. According to the CEN-CENELEC Internal Regulations, the national
14、standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuani
15、a, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 6320:2017 has been approved by CEN as EN ISO 6320:2017 without any modification. BS EN ISO 6320:2017ISO 6320
16、:2017(E)Foreword iv1 Scope . 12 Normative reference . 13 Terms and definitions . 14 Principle 15 Reagents 26 Apparatus . 27 Sampling 28 Preparation of test sample . 29 Procedure. 29.1 Calibration of the instrument . 39.2 Determination . 310 Calculation 311 Precision . 411.1 Interlaboratory test. 411
17、.2 Repeatability . 411.3 Reproducibility . 412 Test report . 4Annex A (normative) Results of an interlaboratory test 5Bibliography 6 ISO 2017 All rights reserved iiiContents PageBS EN ISO 6320:2017ISO 6320:2017(E)ForewordISO (the International Organization for Standardization) is a worldwide federat
18、ion of national 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 committe
19、e. International 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.The procedures used to develop this document and th
20、ose intended for its further maintenance are described 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
21、(see www .iso .org/ directives).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. Details of any patent rights identified during the development of the
22、 document will be in the Introduction and/or on 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 voluntary nature of standa
23、rds, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www .iso .org/ iso/ foreword .html.This document was p
24、repared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 11, Animal and vegetable fats and oils.This fifth edition cancels and replaces the fourth edition (ISO 6320:2000), of which it constitutes a minor revision by the addition of an exclusion for fat coming from milk and milk produ
25、cts.iv ISO 2017 All rights reservedBS EN ISO 6320:2017INTERNATIONAL STANDARD ISO 6320:2017(E)Animal and vegetable fats and oils Determination of refractive index1 ScopeThis document specifies a method for the determination of the refractive index of animal and vegetable fats and oils.Milk and milk p
26、roducts (or fat coming from milk and milk products) are excluded from the scope of this document.2 Normative referenceThe following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition
27、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 sampleISO 5725-1, Accuracy (trueness and precision) of measurement methods and results Part 1: General principles an
28、d definitionISO 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 method3 Terms and definitionsFor the purposes of this document, the following terms and definitions a
29、pply.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 :/ www .iso .org/ obp3.1refractive index (of a medium)ratio of the velocity o
30、f light of a definite wavelength in a vacuum to its velocity in the mediumNote 1 to entry: In practice, the velocity of light in air is used in place of that in a vacuum and, unless otherwise specified, the selected wavelength is the mean wavelength of the sodium D lines (589,6 nm).Note 2 to entry:
31、The refractive index of a given substance varies with the wavelength of the incident light and with temperature. The notation used is ntD, where t is the temperature in degrees Celsius.4 PrincipleBy means of a suitable refractometer, the refractive index of a liquid sample is measured at a specified
32、 temperature. ISO 2017 All rights reserved 1BS EN ISO 6320:2017ISO 6320:2017(E)5 ReagentsUse only reagents of recognized analytical grade and distilled or demineralized water or water of equivalent purity.5.1 Ethyl laurate, of quality suitable for refractometry, and of known refractive index.5.2 Hex
33、ane, or other suitable solvents, such as light petroleum, acetone or toluene, for cleaning the prism of the refractometer.6 ApparatusUsual laboratory equipment and, in particular, the following.Modern digital refractometers may be used. The manufacturers instructions should be followed in this case.
34、6.1 Refractometer, for example of the Abb type, suitable for measurements of refractive index to within 0,000 1 over the range nD= 1,300 to nD= 1,700.6.2 Light source: sodium vapour lampWhite light can also be used if the refractometer is fitted with an achromatic compensation system.6.3 Glass plate
35、, of known refractive index.6.4 Water bath, thermostatically controlled, with a circulation pump, and capable of being maintained to the nearest 0,1 C.6.5 Water bath, capable of being maintained at the temperature at which the measurements are to be made (in the case of solid samples).7 SamplingIt i
36、s important that the laboratory receive a sample which is truly representative and has not been damaged or changed during transportation 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 test samplePrepare th
37、e test sample in accordance with ISO 661.The refractive index shall be determined on dried and filtered fats and oils.In the case of a solid sample, transfer the sample prepared in accordance with ISO 661 to a suitable container and place it in the water bath (6.5), set at the temperature at which t
38、he measurements are to be made. Allow sufficient time for the temperature of the sample to stabilize.9 ProcedureNOTE If it is required to check whether the repeatability requirement (see 11.2) is met, carry out two single determinations in accordance with 9.1 and 9.2.2 ISO 2017 All rights reservedBS
39、 EN ISO 6320:2017ISO 6320:2017(E)9.1 Calibration of the instrumentVerify the calibration of the refractometer (6.1) by measuring the refractive index of the glass plate (6.3) in accordance with the manufacturers instructions, or by measuring the refractive index of the ethyl laurate (5.1).9.2 Determ
40、inationMeasure the refractive index of the test sample at one of the following temperatures:a) 20 C for fats and oils that are completely liquid at this temperature;b) 40 C for fats and oils that are completely melted at this temperature but not at 20 C;c) 50 C for fats and oils that are completely
41、melted at this temperature but not at 40 C;d) 60 C for fats and oils that are completely melted at this temperature but not at 50 C;e) 80 C or above for other fats and oils, for example completely hardened fats or waxes.Maintain the temperature of the prism of the refractometer at the required const
42、ant value by circulating through the instrument water from the water bath (6.4).Monitor the temperature of the water issuing from the refractometer using a suitable precision thermometer. Immediately before the measurement, lower the movable part of the prism to a horizontal position. Wipe the surfa
43、ce of the prism with a soft cloth and then with a piece of cotton wool moistened with a few drops of the solvent (5.2). Allow to dry.Carry out the measurement according to the operating instructions for the instrument being used. Read the refractive index to the nearest 0,000 1 as an absolute value
44、and record the temperature of the prism of the instrument.Immediately after the measurement, wipe the surface of the prism with a soft cloth and then with a piece of cotton wool moistened with a few drops of the solvent (5.2). Allow to dry.Measure the refractive index twice more, calculate the arith
45、metic mean of the three measurements and take this as the test result.10 CalculationIf the difference between the measurement temperature, t1, and the reference temperature, t, is less than 3 C, the refractive index, ntD, at the reference temperature, t, is given by Formula (1):nn ttFttDD=+11() (1)w
46、heret1is the measurement temperature, in degrees Celsius;t is the reference temperature (see 9.2), in degrees Celsius;F is the factor equal to0,000 35 at t = 20 C,0,000 36 at t = 40 C, t = 50 C and t = 60 C,0,000 37 at t = 80 C or above. ISO 2017 All rights reserved 3BS EN ISO 6320:2017ISO 6320:2017
47、(E)If the difference between the measurement temperature, t1, and the reference temperature, t, is 3 C or more, the result should be discarded and a fresh determination made.Report the result rounded to the fourth decimal place.11 Precision11.1 Interlaboratory testDetails of an interlaboratory test
48、on the precision method are summarized in Annex A. The values derived from this test may not be applicable to concentration ranges and matrices other than those given.11.2 RepeatabilityThe absolute difference between two independent single test results, obtained using the same method on identical te
49、st material in the same laboratory by the same operator using the same equipment within a short interval of time, will in no more than 5 % of cases be greater than the repeatability limit, r, given in Annex A.11.3 ReproducibilityThe absolute difference between two single test results, obtained using the same method on identical test material in different laboratories with different operators using different equipment, will in no more than 5 % of cases be greater than the reproducibility limit, R, given in Annex A.12 Tes
