BS 684-1 14-1998 Methods of analysis of fats and fatty oils - Physical methods - Determination of Lovibond colour《脂肪和油脂分析方法 第1部分 物理法 第14节 Lovibond比色测定》.pdf

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1、BRITISH STANDARD BS 684-1.14: 1998 ISO 15305: 1998 Methods of analysis of fats and fatty oils Part 1: Physical methods Section 1.14: Determination of Lovibondcolour ICS 67.200.10BS684-1.14:1998 This British Standard, having been prepared under the directionof the Consumer Products and Services Secto

2、r Committee, was published underthe authority of the Standards Committee and comesinto effect on 15December1998 BSI 06-1999 ISBN 0 580 30768 9 National foreword This British Standard reproduces verbatim ISO15305:1998 and implements it as the UK national standard. It supersedes BS684-1.14:1987 which

3、is withdrawn. The UK participation in its preparation was entrusted to Technical Committee AW/11, Animal and vegetable fats and oils, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation

4、, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implem

5、ent international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purpor

6、t to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cov

7、er, pages i and ii, theISO title page, page ii, pages 1 to 4 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date Comm

8、entsBS684-1.14:1998 BSI 06-1999 i Contents Page National foreword Inside front cover Foreword iii 1 Scope 1 2 Normative reference 1 3 Principal 1 4 Apparatus 1 5 Requirements for operators 2 6 Sampling 2 7 Preparation of test sample 2 8 Procedure 2 9 Expression of results 2 10 Precision 2 11 Test re

9、port 3 Annex A (informative) Results of an interlaboratory trial 4 Annex B (informative) Bibliography 4 Table 1 Repeatability and reproducibility limits 3 Table A.1 Results of interlaboratory trial 4ii blankBS684-1.14:1998 ii BSI 06-1999 Foreword ISO (the International Organization for Standardizati

10、on) is a worldwide federation 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 re

11、presented on that committee. 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. Draft International Stan

12、dards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least75% of the member bodies casting a vote. International Standard ISO15305 was prepared by ISO/TC34, Agricultural food products, Subcommittee

13、SC11, Animal and vegetable fats and oils. Annex A and Annex B of this International Standard are for information only. Descriptors: Agricultural products, food products, animal fats, vegetable fats, animal oils, vegetable oils, tests, determination, colour.BS684-1.14:1998 BSI 06-1999 1 1 Scope This

14、International Standard specifies a method for the determination of the Lovibond colour of animal and vegetable fats and oils. 2 Normative reference The following standard contains provision which, through reference in this text, constitute provisions of this International Standard. At the time of pu

15、blication, the edition indicated was 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 edition of the standard indicated below. Members of IEC and ISO maintain register

16、s of currently valid International Standards. ISO 661:1989, Animal and vegetable fats and oils Preparation of test sample. 3 Principle The colour of the light transmitted through a known path length of liquid fat or oil is matched with the colour of the light originating from the same source transmi

17、tted through glass colour standards. The results are conventionally expressed in Lovibond units. 4 Apparatus Usual laboratory apparatus and, in particular, the following. 4.1 Colorimeter The Lovibond Universal tintometers Model F (BS684) and Model F/C are suitable 1) . NOTEThe older Models AF905 and

18、 AF900/C Model E tintometers are suitable but no longer available. The LovibondAF710, Lovibond Schofield, Wesson and AOCScolorimeters areNOT suitable. 4.2 Lighting cabinet Any of the models given in 4.2.1 and 4.2.2 are suitable. 4.2.1 Models F (BS684) and Model F/C The tintometer shall be maintained

19、 in a good, clean condition in accordance with the manufacturers instructions. The viewing tube shall contain a Skan Blue daylight correction filter and a diffusing lens, and shall have a field of view subtending2 at the eye. It shall be mounted in the cabinet such that the sample and the white refe

20、rence field are viewed at60 to the normal. 4.2.2 Tintometer AF905/E, AF900/C and Model E These are painted internally matt white and contain, behind ground glass diffusing screens, two60W pearl (uncoated) lamps operated at the correct mains voltage and positioned one on either side of the viewing tu

21、be so that each illuminates the white reflecting reference surface at an angle of45. BOTH lamps shall be changed as soon as either envelope shows signs of discoloration and, in any event, after100h of use. A suitable logging system shall be used to register lamp usage. The viewing tube shall contain

22、 a Skan Blue daylight correction filter and a diffusing lens and shall have a field of view subtending2 at the eye. It shall be mounted in the cabinet such that the sample and white reference field are viewed at90 to the normal. The lighting cabinet, diffusing screens and reflectance surfaces shall

23、be kept free from stains and regularly cleaned. The internal paintwork shall be inspected regularly for ageing/discoloration and shall be repainted matt white when the surfaces become darker than Munsell Notation5Y9/1 1) . The viewing tube shall be maintained in accordance with the manufacturers ins

24、tructions. 4.3 Colour racks These shall be fitted with colourless compensating slides on the lower section and shall contain glass colour standards (in Lovibond units) as follows: The colour standards shall be kept clean and free from oil and grease by wiping with cotton buds dipped in warm water co

25、ntaining detergent and dried by wiping with cotton wool. Solvents shall not be used for cleaning. NOTECertified Conformance glass colour standards (available from The Tintometer Ltd), can be used to check that the instrument is operating correctly. 4.4 Spillage tray This is required for the Model Ty

26、pe E only. 4.5 Glass cells These shall be made of good quality optical glass and shall have a good standard finish, with optical path lengths as follows: 1) The Lovibond tintometers and the Munsell Notation5Y9/1 are available from The Tintometer Ltd, Waterloo Road, Salisbury, Wiltshire, SP1 2JY, Uni

27、ted Kingdom. These tintometers are examples of products available commercially. This information is given for the convenience of users of this International Standard and does not constitute an endorsement by ISO of these products. Red 0,1 to 0,9 1,0 to 9,0 10,0 and 70,0 Yellow 0,1 to 0,9 1,0 to 9,0

28、10,0 to 70,0 Blue 0,1 to 0,9 1,0 to 9,0 10,0 to 40,0 Neutral 0,1 to 0,9 1,0 to 3,0BS684-1.14:1998 2 BSI 06-1999 1,6 mm (1/16 inch); 3,2 mm (1/8inch);6,4mm (1/4inch);12,7mm(1/2inch); 25,4mm (1inch); 76,2mm (3inch); 133,4mm (5 1/4inch). 5 Requirements for operators All operators shall have satisfactor

29、y colour vision and shall have their colour vision retested at intervals of no longer than5years. The colour vision tests shall be carried out by a qualified optician. Operators who normally wear spectacles or contact lenses may continue to wear them, but tinted or light-sensitive spectacles/lenses

30、shall not be worn. 6 Sampling It is important that the laboratory receive a sample that 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 ISO5

31、555. 7 Preparation of test sample Prepare the sample in accordance with ISO661. The fat or oil shall be completely liquid, clear and bright when the determination is made. 8 Procedure 8.1 The determination shall be carried out in subdued ambient light. In particular, the tintometer shall NOT be set

32、up facing a window or in direct sunlight. If the prepared sample is not fully liquid at room temperature, heat it to a temperature about10C above its melting point. The glass cell (4.5) shall be thoroughly clean and dry and, if necessary, pre-warmed so that no solid matter separates from the sample

33、during the colour determination. 8.2 Pour the liquid sample into a glass cell (4.5) of sufficient optical path length to give colour readings within the ranges given in 4.3. 8.3 Place the cell containing the sample within the lighting cabinet (4.2) so that it is close to the viewing tube. 8.4 Close

34、the lid of the lighting cabinet and immediately determine the colour of the sample by using the colour racks (4.3), initially in the ratio of10,0yellow to1,0red Lovibond units (in all sections), to obtain an approximate match, then correcting, without necessarily maintaining the ratio of10yellow to1

35、red and using the minimum of blue OR neutral filters (blue and neutral filters shall not be used simultaneously) until an accurate colour match is obtained. Not more than9,0blue or3,0neutral shall be used. CAUTION: The operator shall look away from the eyepiece after each30s of matching to avoid eye

36、 fatigue. NOTE 1Colourless compensating slides are necessary to balance the brightness of the fields of view of the sample and colour filters due to the light loss at the glass surfaces. NOTE 2In order to make a precise colour match, it may be necessary to introduce neutral or blue glasses, but NOT

37、both, to reduce the brightness of the standard relative to that of the sample. 8.5 The test shall be carried out by two trained operators and the mean values reported. If the results of the two operators vary too widely, then a third operator shall carry out the test. The mean value of the closest t

38、wo readings shall be reported. 9 Expression of results Express the results in terms of the following: a) the numbers of red, yellow and blue or neutral standards necessary to obtain the match; b) the optical path length of the cell used. Only standard cell sizes (4.5) shall be used. Colour measureme

39、nts taken in one cell size shall not be used to calculate colour values for another cell size. 10 Precision 10.1 Interlaboratory test Details of an interlaboratory test on the precision of the method are given in Annex A. The values derived from this interlaboratory test may not be applicable to con

40、centration ranges and matrices other than those given. 10.2 Repeatability The absolute difference between two independent single test results, obtained with the same method on identical test material in the same laboratory by the same two operators using the same equipment within a short interval of

41、 time, will in not more than5% of cases exceed the repeatability limit (r) given in Table 1.BS684-1.14:1998 BSI 06-1999 3 10.3 Reproducibility The absolute difference between two single test results, obtained with the same method on identical test material in different laboratories by different oper

42、ators using different equipment, will in not more than5% of cases exceed the reproducibility limit (R) given in Table 1. Table 1 Repeatability and reproducibilitylimits 11 Test report The test report shall specify: all information necessary for the complete identification of the sample; the test met

43、hod used, with reference to this International Standard; any operating conditions not specified in this International Standard, or regarded as optional, together with details of any incidents which may have influenced the test results; the results obtained, in Lovibond units. Colour scale Level r R

44、Red: 133,4 mm cell (5 inch) 2 5 0,2 0,7 0,8 2 Yellow: 133,4 mm cell (5 inch) 20 50 3 6 5 12BS684-1.14:1998 4 BSI 06-1999 Annex A(informative) Results of an interlaboratory trial An international collaborative test involving nine laboratories analysing two samples of oils was organized by FOSFA Inter

45、national and the results obtained were subjected to statistical analysis in accordance with ISO5725-1 and ISO5725-2 to give the precision data reported in Table A.1. Table A.1 Results of interlaboratory trial Annex B(informative) Bibliography 1 ISO 5555:1991, Animal and vegetable fats and oils Sampl

46、ing. 2 ISO 5725-1:1994, Accuracy (trueness and precision) of measurement methods and results Part1:General principles and definitions. 3 ISO 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results Part2:Basic method for the determination of repeatability and reproducibility

47、 of a standard measurement method. Sample Palm oil (RBD) Crude palm kernel oil Colour scale: 133,4 mm cell (5 inch) Number of laboratories Number of accepted results Mean value, in Lovibond units Red 9 9 2,3 Yellow 9 9 21,6 Red 9 9 5,0 Yellow 9 7 47,7 Repeatability standard deviation, s r , inLovibo

48、nd units Repeatability limit, r, in Lovibond units 0,07 0,20 1,22 3,42 0,25 0,71 2,35 6,58 Reproducibility standard deviation, s R , inLovibond units Reproducibility limit, R, in Lovibond units 0,29 0,81 1,80 5,04 0,76 2,12 4,34 12,26 NOTERBD means refined, bleached and deodorized.blankBS 684-1.14:

49、1998 ISO 15305: 1998 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions BritishStandards are updated by amendment or revision. Users of BritishStandards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services.