1、BRITISH STANDARD BS ISO 6656:2002 Animal and vegetable fats and oils Determination of polyethylene-type polymers ICS 67.200.10 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS ISO 6656:2002 This British Standard, having been prepared under the direction of the Consumer Produc
2、ts and Services Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 23 May 2002 BSI 23 May 2002 ISBN 0 580 39657 6 National foreword This British Standard reproduces verbatim ISO 6656:2002 and implements it as the UK national stan
3、dard. It supersedes BS 684-2.26:1986 (1995) which is withdrawn.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: A list of organizations represented on this committee can be obtained on request to
4、 its secretary. Cross-references The British Standards which implement 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
5、 Standards Electronic Catalogue. A British Standard does not purport 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. aid enqu
6、irers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This doc
7、ument comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 6, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsINTE
8、RNATIONAL STANDARD ISO 6656 Second edition 2002-04-15 Reference number ISO 6656:2002(E) Animal and vegetable fats and oils Determination of polyethylene-type polymers Corps gras dorigines animale et vgtale Dosage des polymres de type polythylneISO 6656:2002(E) ii ISO 2002 Ar llithgr seresvde This FD
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13、 ISO copyrithg fofiec tsop esaCela 65 G 1121-HCeneva 02 T.le + 22 14 10 947 11 Fxa + 14 47 2290 9 74 E-liam cpoyrigthsio.ch Web wwwsi.oc.h Prni detni SztiwerldnaISO 6656:2002(E)iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodie
14、s (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. International organizations,
15、 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 rules given in the ISO
16、/IEC Directives, Part 3. 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 least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some
17、of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. International Standard ISO 6656 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 11, Animal and vegetable
18、fats and oils. This second edition cancels and replaces the first edition (ISO 6656:1984), which has been editorially revised to include warning notices about the use of certain solvents. Annex A of this International Standard is for information only.ISO 6656:2002(E) iv Introduction The presence of
19、polyethene-type polymers, which originate from packaging materials, can cause serious difficulties in the processing of fats, as they can lead to deposits and blockages in pipes, valves, etc. In the manufacturer of soap, they may lead to the appearance of fibre marbling and undesirable specks.INTERN
20、ATIONAL STANDARD ISO 6656:2002(E)1 Animal and vegetable fats and oils Determination of polyethylene-type polymers WARNING The method described in this International Standard requires the use of chloroform and tetrachloroethylene. These are toxic and ozone-depleting substances. Avoid inhalation of an
21、d exposure to these solvents. Work in a fume cupboard when handling these solvents and solutions thereof. 1 Scope This International Standard specifies the reference method for the determination of polyethylene-type polymers in animal and vegetable fats and oils. It has been established that below o
22、f polymers per kilogram the precision of the method is insufficient (see the results for tallow 1 in Table A.1). This method is used for animal fats and oils in particular. 2 Term and definition For the purposes of this International Standard, the following term and definition applies. 2.1 polyethye
23、ne-type polymers impurities which are soluble in boiling tetrachloroethylene EXAMPLE Polyethylenes which originate from packaging materials. 3 Principle After acid treatment to decompose any soaps present, a test portion is dissolved in chloroform (which leaves polyethylene-type polymers in suspensi
24、on) and filtered through a sintered filter crucible containing a mat of filter aid. The crucible and its contents are washed, dried and weighed. Polyethylene-type polymers are extracted from the insoluble matter by boiling tetrachloroethylene. The crucible with its contents are dried and weighed aga
25、in. 4R e a g e n t s Use only reagents of recognized analytical grade and distilled or deionized water or water of equivalent purity. 4.1 Methanol, containing not more than (by mass) of water. 4.2 Acetone. 4.3 Chloroform. 4.4 Tetrachloroethylene. 4.5 Hydrochloric acid, ethanolic solution. 50 mg 0,5
26、%ISO 6656:2002(E) 2 Mix 1 volume of hydrochloric avid ( ) with 9 volumes of (by volume) ethanol. 4.6 Diatomaceous earth-type filter aid, acid washed. 5 Apparatus WARNING Apparatus made of plastic is likely to be affected by solvents (particularly chloroform or tetrachloroethylene). Care shall be tak
27、en to ensure that the solvents used do not come into contact with plastics. Usual laboratory equipment and, in particular, the following. 5.1 Beakers, of capacity . 5.2 Filter flasks, of capacities and . 5.3 Sintered filter crucibles, of porosity grade P 40 ( to ). 5.4 Desiccator. 5.5 Magnetic stirr
28、er, with heater. 5.6 Oven, capable of being maintained at . 5.7 Analytical balance. 6 Sampling Because the polymers are often heterogeneously distributed in a lot, particular care is necessary to obtain representative samples. It is important the laboratory receive a sample which is truly representa
29、tive 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 ISO 5555. 7 Procedure WARNING Avoid contact of reagents with the skin. Do no inhale the vapours. Perform all op
30、erations under a suitable fume hood. 7.1 Preparation of test sample Heat the sample of fat or oil to to . Stir the sample for to to ensure complete homogenization. 7.2 Test portion Weigh, to the nearest , about of the test sample (7.1) into a beaker (5.1). For samples expected to contain more than o
31、f polyethylene-type polymers per kilogram, the test portion may be reduced to . 20 = 1,19 g/ml 95 % 1 000 ml 250 ml 1 000 ml 16m4 0 m 103 C 2 C 110 C 120 C 3 min 4 min 0,1 g 100 g 1 000 ml 500 mg 50 gISO 6656:2002(E)3 7.3 Acid treatment Add of the ethanolic hydrochloric acid (4.5) to the test portio
32、n, cover the beaker and stir on the magnetic stirrer (5.5) for at to . Cool to below , then add of chloroform (4.3) and stir until the fat or oil is dissolved (the solution may not be clear). Add of the filter aid (4.6) suspended in of chloroform (to avoid the formation of lumps). 7.4 Determination
33、7.4.1 Prepare a filter mat by suspending about of the filter aid (4.6) in of chloroform and filtering through the sintered filter crucible (5.3). Using suction if necessary, filter the contents of the beaker (stirred immediately before filtration) into a filter flask (5.2). 7.4.2 Rinse the beaker wi
34、th about of chloroform and pour the rinsings slowly through the sintered filter crucible under suction, keeping the chloroform level in the crucible about above the filter mat. Repeat the rinsing with of methanol (4.1), taking the same precautions. 7.4.3 Repeat the washing procedure, rinsing the cru
35、cible alternately with chloroform and methanol ( portions) until a total of of chloroform and of methanol has been used. Continue suction until the crucible is dry. 7.4.4 Wash the underside of the crucible with chloroform. Wash the contents of the crucible twice under suction withof acetone (4.2) in
36、 order to remove absorbed water. Suck air through the crucible for . 7.4.5 When the crucible appears to be dry, place it in the oven (5.6), set at , and leave for to . 7.4.6 Allow the crucible to cool in the desiccator (5.4) for and weigh to the nearest . Repeat the drying, cooling and weighing proc
37、edures until the difference between two successive weighings does not exceed . Record the mass ( ). 7.4.7 Warm the crucible and its contents to in the oven (5.6), then wash the contents of the crucible withof boiling tetrachloroethylene (4.4), without suction if possible, using a clean dry filter fl
38、ask (5.2) to collect the filtrate. Repeat the washing procedure four more times, using portions of boiling tetrachloroethylene each time. Suck air through the crucible for . 7.4.8 Wash the crucible with of acetone (4.2) to remove traces of tetrachloroethylene and suck air through the crucible for .
39、7.4.9 Place the crucible in the oven (5.6), set at , and leave for to . Allow the crucible to cool in the desiccator (5.4) for then weigh to the nearest . 7.4.10 Repeat the washings with boiling tetrachloroethylene (see 7.4.7) and with acetone (see 7.4.8) and the drying, cooling and weighing procedu
40、res (see 7.4.9) until the difference between two successive weighings does not exceed . Record the mass ( ). 7.5 Number of determinations Carry out two determinations on the same test sample. 8 Expression of results The polyethylene-type polymer content, , expressed in milligrams per kilogram, is eq
41、ual to 75 ml 5 min 60 C7 0 C 35 C 270 ml 1,0 g 30 ml 0,5 g 30 ml 1 000 ml 50 ml 5mm 50 ml 50 ml 150 ml 100 ml 25 ml 1min 103 C 15 min 30 min 30 min 0,1 mg 1mg m 1 103 C 25 ml 250 ml 25 ml 2min 50 ml 2min 103 C 15 min 30 min 30 min 0,1 mg 1mg m 2 w w= m 1 m 2 m 0 10 6ISO 6656:2002(E) 4 where is the m
42、ass, in grams, of the test portion (7.2); is the mass, in grams, of the crucible and insoluble matter before extraction (7.4.6); is the mass, in grams, of the crucible and insoluble matter after extraction (7.4.10). Take as the result the arithmetic mean of the values obtained in the two determinati
43、ons. 9P r e c i s i o n Details of an interlaboratory test on the precision of the method are summarized in annex A. The values derived from this interlaboratory test may not be applicable to concentration ranges and matrices other than those given. 10 Test report The test report shall specify: all
44、information necessary for the complete identification of the sample; the sampling method used, if known; the test method used, with reference to this International Standard; all operating details not specified in this International Standard, or regarded as optional, together with details of any inci
45、dents which may have influenced the test result(s); the test result(s) obtained or, if the repeatability has been checked, the final result obtained. m 0 m 1 m 2ISO 6656:2002(E)5 Annex A (informative) Results of interlaboratory test An interlaboratory test, carried out at the international level, in
46、 which 10 laboratories participated, each carrying out a variable number of determinations, gave the statistical information (derived in accordance with ISO 5725:1986) summarized in Table A.1. Table A.1 Tallow 1 Tallow 2 Number of laboratories retained after eliminating outliers 10 9 Mean, 41184 Sta
47、ndard deviation of repeatability ( ), 8 15 Coefficient of variation of repeatability, 20 8,4 Repeatability limit ( ) ( ), 23 24 Standard deviation of reproducibility ( ), 14 33 Coefficient of variation of reproducibility, 34 18 Reproducibility limit ( ) ( ), 39 92 mg/kg s r mg/kg % r 2,83s r mg/kg s
48、 R mg/kg % R 2,83s R mg/kgISO 6656:2002(E) 6 Bibliography 1 ISO 5555, Animal and vegetable fats and oils Sampling 2 ISO 5725:1986, Precision of test methods Determination of repeatability and reproducibility by inter- laboratory tests 3 ISO 5725-1:1994, Accuracy (trueness and precision) of measureme
49、nt methods and results Part 1: General principles and definitions 4 ISO 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement methodBS ISO 6656:2002 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the int
